@article {pmid508236,
year = {1979},
author = {Fermor, U and Huber, H and Neuhaus, KL and Schmiel, FK and Spiller, P},
title = {Measurement of flow velocity in the model circulation by videodensitometry. Methodological investigations.},
journal = {Basic research in cardiology},
volume = {74},
number = {4},
pages = {361-377},
pmid = {508236},
issn = {0300-8428},
mesh = {*Blood Flow Velocity ; Densitometry/*methods ; *Models, Structural ; *Television ; },
abstract = {The relation between videodensitometrically measured front velocity and electromagnetically assessed flow was examined in a circulatory model with continuous as well as pulsatile flow (89 experiments). The diameter of the tubes in the videodensitometric measuring section was 0.305 to 0.518 cm. A linear correlation was proved in flow velocities up to Reynold's number Re = 225. The exact flow, measured electromagnetically, was overestimated in continuous flow by 21% (r = 0.99, Syx = +/- 14.5 ml/min) and in pulsatile flow by 24% (r = 0.98, Syx = +/- 20.8 ml/min). In view of these results the phasic and average flow can be calculated accurately using videodensitometric techniques.},
}

*Blood Flow Velocity
Densitometry/*methods
*Models, Structural
*Television

@article {pmid608670,
year = {1977},
author = {Nachtigall, W},
title = {[On the significance of Reynold's number and the fluid mechanical phenomena connected to it in swimming physiology and flight biophysics (author's transl)].},
journal = {Fortschritte der Zoologie},
volume = {24},
number = {2-3},
pages = {13-56},
pmid = {608670},
issn = {0071-7991},
mesh = {Animals ; *Biomechanical Phenomena ; *Flight, Animal ; *Locomotion ; Swimming ; },
}

Animals
*Biomechanical Phenomena
*Flight, Animal
*Locomotion
Swimming

@article {pmid2252781,
year = {1990},
author = {Van Meurs, KP and Mikesell, GT and Seale, WR and Short, BL and Rivera, O},
title = {Maximum blood flow rates for arterial cannulae used in neonatal ECMO.},
journal = {ASAIO transactions},
volume = {36},
number = {3},
pages = {M679-81},
pmid = {2252781},
issn = {0889-7190},
mesh = {Blood Flow Velocity/*physiology ; *Catheters, Indwelling ; Equipment Design ; Erythrocyte Deformability/*physiology ; Extracorporeal Membrane Oxygenation/*instrumentation ; Hemolysis/*physiology ; Humans ; Infant, Newborn ; Models, Cardiovascular ; Respiratory Distress Syndrome, Newborn/*physiopathology ; Rheology ; },
abstract = {The arterial cannulae used in neonatal ECMO cause hemolysis and red blood cell damage at elevated blood flows. Hemolysis in extracorporeal circuits has been found to occur with shear stress greater than 132 dynes/cm2, turbulence as measured by Reynold's number greater than 1,000, and velocity greater than 120 to 200 cm/sec. These parameters need to be considered when sizing the proper arterial cannula for a required flow rate. In-vitro measurements of the pressure drop across six arterial cannulae at varying flow rates were performed using human blood with a hematocrit of 43%. Shear stress, Reynold's number, velocity, and pressure drop were calculated for each catheter at flow rates from 50 to 1,000 cc/min. The maximum mean flow rate to maintain the shear stress, Reynold's number, velocity, and pressure drop within the accepted range, was determined for each cannula. Recommended maximum blood flow rates for each of the six cannulae are given. Internal diameter, length, and cannula geometry appear to be the factors most affecting the flow achievable without causing red blood cell damage and hemolysis. Ten French Biomedicus, 10 French Cook, and 10 French Elecath arterial cannulae appear best suited to deliver the range of blood flow rates used in neonatal ECMO.},
}

Blood Flow Velocity/*physiology
*Catheters, Indwelling
Equipment Design
Erythrocyte Deformability/*physiology
Extracorporeal Membrane Oxygenation/*instrumentation
Hemolysis/*physiology
Humans
Infant, Newborn
Models, Cardiovascular
Respiratory Distress Syndrome, Newborn/*physiopathology
Rheology

@article {pmid2780523,
year = {1989},
author = {Vogel, J and Smith, HJ and Müller, E},
title = {[To what extent are oscillometric data of a simple resistor-volume model physically recordable?].},
journal = {Pneumologie (Stuttgart, Germany)},
volume = {43},
number = {7},
pages = {324-330},
pmid = {2780523},
issn = {0934-8387},
mesh = {*Airway Resistance ; Algorithms ; Humans ; Lung/physiopathology ; Lung Volume Measurements/*instrumentation ; *Models, Biological ; Oscillometry/*instrumentation ; Pulmonary Emphysema/physiopathology ; *Pulmonary Ventilation ; },
abstract = {To obtain data on the volume-dependence of the oscillatory parameters of the Siregnost FD 5, we investigated the course of iso-volume and iso-resistance lines in a simple mechanical resistor-volume model in the different coordinate systems, initially in the absence of additional superimposed stationary flow. While the P-psi diagram reveals no uniform course, and no preferential relationship of changes in resistance to P or Ros, or of changes in volume to psi, such a relationship develops on transformation to the Rre-phi and the Rre-X diagram. Rre proves to contain not only the purely resistor component, but also a reactance-proportional or inversely volume-proportional component, which is apparently due to internal friction resulting from volume compression. On the other hand, reactance is almost totally derivable from volume compression. With reference to the theoretical Franken model and others (1981), we discussed the influence of various physical factors on the impedance of a tube segment, and the different volume-dependence of impedance of closed- and open-ended cylindrical tubes. Further work on the theoretical consideration of the forced oscillation technique will examine the influence of additional superimposed stationary flow, which has a considerable effect on the resistor-volume model. Furthermore, the critical value of Reynold's number may be expected to be exceed in the FD 5 reference tube already at low respiratory flow.},
}

*Airway Resistance
Algorithms
Humans
Lung/physiopathology
Lung Volume Measurements/*instrumentation
*Models, Biological
Oscillometry/*instrumentation
Pulmonary Emphysema/physiopathology
*Pulmonary Ventilation

@article {pmid2949490,
year = {1986},
author = {Steiger, HJ and Reulen, HJ},
title = {Low frequency flow fluctuations in saccular aneurysms.},
journal = {Acta neurochirurgica},
volume = {83},
number = {3-4},
pages = {131-137},
pmid = {2949490},
issn = {0001-6268},
mesh = {*Cerebrovascular Circulation ; Humans ; Intracranial Aneurysm/*physiopathology ; Models, Biological ; Rheology ; Rupture, Spontaneous ; },
abstract = {Intra-operative Doppler recordings were carried out on cerebral saccular aneurysms in 12 patients. Distinct fluctuations of flow superimposed on the pulse wave were seen in 6 patients. The fluctuations appeared to be periodic with measured period lengths of 60 to 150 msec. In 3 other patients flow irregularities could be discerned acoustically but a definite periodicity could not be visualized on screen. In 3 patients flow appeared smooth during the entire pulse cycle, acoustically as well as visually. Concomitant flow observations in glass model aneurysms also revealed flow instabilities in certain aneurysm types at a Reynold's number of 300. All observed irregularities of flow were observed in zones of deceleration of flow in the models. Signs of fully developed turbulence were not found, neither in human aneurysms nor in the glass models. It appears likely that the fluctuations of flow induce vibrations of the aneurysmal wall and contribute to aneurysm progression and eventual rupture.},
}

*Cerebrovascular Circulation
Humans
Intracranial Aneurysm/*physiopathology
Models, Biological
Rheology
Rupture, Spontaneous

@article {pmid6652213,
year = {1983},
author = {Jones, RD and Lemanski, CL and Jones, TJ},
title = {Theory of attachment in Giardia.},
journal = {Biophysical journal},
volume = {44},
number = {2},
pages = {185-190},
pmid = {6652213},
issn = {0006-3495},
mesh = {Adhesiveness ; Giardia/*physiology ; *Models, Biological ; },
abstract = {Using a low Reynold's number hydrodynamic model, the adhesive force in Giardia is calculated. It is shown that this force is larger than typical forces that would tend to detach the organism.},
}

Adhesiveness
Giardia/*physiology
*Models, Biological

@article {pmid6747536,
year = {1984},
author = {Batty, RS},
title = {Development of swimming movements and musculature of larval herring (Clupea harengus).},
journal = {The Journal of experimental biology},
volume = {110},
number = {},
pages = {217-229},
doi = {10.1242/jeb.110.1.217},
pmid = {6747536},
issn = {0022-0949},
mesh = {Animals ; Fishes/*growth & development/physiology ; Muscle Development ; Swimming ; },
abstract = {A kinematic analysis was made of swimming of larval herring Clupea harengus L. Swimming style was found to change with growth and development; the amplitude of swimming movements of early post-yolk-sac larvae increases linearly towards the tail, a style of swimming which relies mainly on resistive forces for propulsion. Later, after the caudal and dorsal fins have developed, the swimming style changes, in response to an increase in Reynold's Number, such that inertial forces are more important. In this type of swimming the amplitude increases more rapidly than linearly towards the tail. The distribution of red and white muscle fibre types was studied in relation to development. On hatching, red muscle fibres were found to be arranged as a single layer on the outside of the myotomes. They develop into the adult distribution, concentrated at the midline of the flank near the skin, only after the gills and circulation become fully functional.},
}

Animals
Fishes/*growth & development/physiology
Muscle Development
Swimming

@article {pmid7409200,
year = {1980},
author = {Macklem, PT},
title = {The paradoxical nature of pulmonary pressure-flow relationships.},
journal = {Federation proceedings},
volume = {39},
number = {10},
pages = {2755-2758},
pmid = {7409200},
issn = {0014-9446},
mesh = {Animals ; Bronchi/physiology ; Humans ; Lung/*physiology ; Mathematics ; Models, Biological ; Pressure ; Respiration ; Trachea/physiology ; },
abstract = {Most equations proposed to describe pulmonary pressure-flow relationships are inadequate because the "constants" that contain the airway geometry are not, in fact, constant but vary as the distribution of Reynold's number Re varies with flow or gas density. However, even when the normalized pressure drop is plotted against Re (Moody diagram), different relationships are found for different gas mixtures. Thus the normalized pressure drop is a function of one or more variables in addition to Re. As long as this variable or variables remain unknown, the pulmonary pressure-flow relationships will remain paradoxical.},
}

Animals
Bronchi/physiology
Humans
Lung/*physiology
Mathematics
Models, Biological
Pressure
Respiration
Trachea/physiology

@article {pmid7877228,
year = {1995},
author = {Staalsen, NH and Ulrich, M and Winther, J and Pedersen, EM and How, T and Nygaard, H},
title = {The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.},
journal = {Journal of vascular surgery},
volume = {21},
number = {3},
pages = {460-471},
doi = {10.1016/s0741-5214(95)70288-1},
pmid = {7877228},
issn = {0741-5214},
mesh = {Anastomosis, Surgical/*methods ; Animals ; Aorta/diagnostic imaging/physiology/*surgery ; *Blood Flow Velocity ; Blood Vessel Prosthesis ; Hemodynamics ; Hemorheology ; Swine ; Ultrasonography, Doppler, Color ; },
abstract = {PURPOSE: The purpose of this article was to study the influence of the anastomosis angle on the flow fields at end-to-side anastomoses in vivo.

METHODS: Polyurethane grafts of similar internal diameter to that of the abdominal aorta (8 mm) were implanted from the suprarenal to the infrarenal level in 10 pigs. Three angles of standardized distal end-to-side anastomoses (90 degrees, 45 degrees, and 15 degrees) were studied. The anatomic position of the anastomoses was constant, the proximal outflow segment was occluded, and the flow rate through the graft was controlled. Flow visualization was accomplished by a color-flow Doppler ultrasound system.

RESULTS: The angulation was reproduced within 10%. Gross hemodynamic parameters were stable, and the similarity parameters were typical for peripheral bypasses (mean Reynold's number is 424 and Womersley's parameter is 5.9). The flow fields were clearly dependent on the anastomosis angle. A zone of recirculation (approximately 5% of the flow area), extending from the toe to one diameter downstream, was found in the 45-degree and 90-degree anastomoses. No flow disturbances were detected at the toe and one diameter downstream with an anastomosis angle of 15 degrees. At the heel different recirculating flow patterns were found in the different anastomoses.

CONCLUSION: The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.},
}

Anastomosis, Surgical/*methods
Animals
Aorta/diagnostic imaging/physiology/*surgery
*Blood Flow Velocity
Blood Vessel Prosthesis
Hemodynamics
Hemorheology
Swine
Ultrasonography, Doppler, Color

@article {pmid8125899,
year = {1993},
author = {Quail, AW and Cottee, DB and White, SW},
title = {Limitations of a pulsed Doppler velocimeter for blood flow measurement in small vessels.},
journal = {Journal of applied physiology (Bethesda, Md. : 1985)},
volume = {75},
number = {6},
pages = {2745-2754},
doi = {10.1152/jappl.1993.75.6.2745},
pmid = {8125899},
issn = {8750-7587},
mesh = {Animals ; Aorta, Abdominal/physiology ; Coronary Circulation/physiology ; Dogs ; Femoral Artery/physiology ; Hematocrit ; Microcirculation/*physiology ; Rabbits ; Renal Artery/physiology ; Rheology/*instrumentation ; Ultrasonics ; },
abstract = {The performance of a new and simplified flow probe construction and the Iowa 545C-4 pulsed Doppler velocimeter was evaluated for measurement of blood flow over several months in small arteries of awake animals. Calibrations were performed over a wide range of intraluminal pressures and physiological flow velocities. Pressure-dependent differences in slope of the Doppler shift-volume flow relationship were detected in some probes. Signal strength was maintained at hematocrits > 10%. Distortion of pulsed Doppler signal peaks occurred in the conscious rabbit at peak aortic velocities, at which Reynold's number for turbulence was exceeded and the Doppler shift surpassed the Nyquist limit of 31.25 kHz for the velocimeter. Although the Doppler shift-volume flow relationship is linear at < 5 kHz, in some cases at higher Doppler shifts and blood flow velocities the relationship may become nonlinear, thus causing the volume flow rate to be underestimated by up to 38%. The cause of this phenomenon may be "aliasing" and/or the consequence of the range control capability of the velocimeter selectively sampling changing velocity profiles and flow disturbances in the central stream at higher velocities.},
}

Animals
Aorta, Abdominal/physiology
Coronary Circulation/physiology
Dogs
Femoral Artery/physiology
Hematocrit
Microcirculation/*physiology
Rabbits
Renal Artery/physiology
Rheology/*instrumentation
Ultrasonics

@article {pmid8511826,
year = {1993},
author = {Bascom, PA and Cobbold, RS and Routh, HF and Johnston, KW},
title = {On the Doppler signal from a steady flow asymmetrical stenosis model: effects of turbulence.},
journal = {Ultrasound in medicine & biology},
volume = {19},
number = {3},
pages = {197-210},
doi = {10.1016/0301-5629(93)90110-a},
pmid = {8511826},
issn = {0301-5629},
mesh = {*Blood Flow Velocity ; Constriction ; Humans ; *Models, Cardiovascular ; Models, Structural ; Rheology ; *Ultrasonography ; },
abstract = {A steady flow model with a 70% (by area) asymmetrical stenosis was used to examine how changing flow regimes (laminar to turbulent) affect the Doppler signal. Human red blood cells (RBCs) (Hct = 42%) in saline were employed at a flow rate corresponding to a Reynold's number of approximately 545. A dilute suspension of 4% fixed RBCs was also used for the purpose of backscattered power comparison. Measurements of the Doppler signal enabled the backscattered power, time domain statistics, frequency spectra, frequency domain statistics, various spectral indices, autocorrelation function and decorrelation time to be calculated as a function of distance from the stenosis. It is shown that the characteristics of the Doppler signal measured at each site provide information on the nature of the insonated flow field and these correlate well with those expected. The results demonstrate that the onset of turbulence not only affects the Doppler spectrum but also has a profound effect on the signal power, the decorrelation time and the signal statistics.},
}

*Blood Flow Velocity
Constriction
Humans
*Models, Cardiovascular
Models, Structural
Rheology
*Ultrasonography

@article {pmid8746940,
year = {1995},
author = {Wellnhofer, E and Biamino, G and Sauer, HU and Trebeljahr, A and Stalke, J and Ragg, C and Oswald, H and Gotze, S and Fleck, E and Felix, R},
title = {Changes of fluid-dynamic parameters in peripheral stenoses with transcutaneous interventions.},
journal = {European heart journal},
volume = {16 Suppl J},
number = {},
pages = {60-70},
doi = {10.1093/eurheartj/16.suppl_j.60},
pmid = {8746940},
issn = {0195-668X},
mesh = {Adult ; Aged ; Aged, 80 and over ; Angiography ; *Angioplasty, Balloon, Laser-Assisted ; Blood Flow Velocity ; Blood Viscosity ; Exercise Test ; Female ; Humans ; Male ; Middle Aged ; Peripheral Vascular Diseases/diagnosis/*physiopathology/therapy ; Ultrasonography, Interventional ; },
abstract = {UNLABELLED: Peripheral vessels provide a useful in vivo haemodynamic model allowing evaluation of local intravascular fluid dynamics. Velocity measurements using a 0.018 inch Doppler-tipped angioplasty guidewire, quantitative angiography and laboratory data were gathered from 45 patients with a total of 48 percutaneous transluminal laser assisted angioplasties (PTLA) in the superficial femoral, in the iliac, in the popliteal artery and in the peroneal artery. From these data, blood flow, whole blood viscosity, Reynold's numbers, Womersley numbers and shear stress were calculated, evaluated as to their changes post PTLA and correlated with clinical improvement at early follow-up. The clinical result was quantified as categorial improvement according to the American Heart Association guidelines. The primary angiographic results of angioplasty were satisfactory in all patients. Clinically 17/45 patients showed a marked, 6/45 a moderate, 18/45 a minimal, and 4/45 no improvement. The mean values of maximal peak velocity at stenosis decreased from 235 +/- 28 cms-1 to 84 +/- 8 cms-1 after PTLA (P < 0.01). The minimal intrastenotic cross section increased from 7.7 +/- 0.9 to 21.9 +/- 1.6 mm2 (P < 0.01). Mean trans-stenotic flow increased after intervention by about 50% (P < 0.01) and improved further by 135% after administration of adenosine triphosphosphate i.a. (P < 0.01). Reynold's numbers were elevated intrastenotically (1285 +/- 198) pre-intervention as compared to values proximal (564 +/- 81) and distal (449 +/- 66) to the stenosis and were reduced significantly (P < 0.05) at stenosis by PTLA, whereas values proximally and distally increased significantly (P < 0.01) post PTLA (proximal 829 +/- 84, intra 773 +/- 107, distal 676 +/- 98). Shear stress, reflecting mechanical interaction between flow and vessel wall, was elevated at stenosis pre-intervention to 44 +/- 8.9 Pa and reduced at post-stenoric vessel sites to 2.4 +/- 0.5 Pa. PTLA caused a decrease in stenosis to 6.3 +/- 1 Pa (P < 0.01) and an increase distally to 4.6 +/- 1 Pa (P < 0.01). Whereas in single stenoses removal of the obstruction was associated with a significant (P < 0.05) increase in trans-stenotic flow and shear stress distally, there was only auenuated increase in trans-stenotic flow in multiple lesions despite an angiographically good PTLA result. Shear stress distally remained low in those patients. Velocities and Reynold's numbers were lower in these vessels even pre PTLA. Residual flow, Reynold's number and minimal cross-section pre-intervention correlated significantly with clinical outcome. Pooling cases with no or minimal, as opposed to those with marked or moderate improvement, 81% of patients were correctly classified using the Reynold's numbers pre- and post-PTLA.

CONCLUSION: Peak velocity monitoring is feasible and safe during angioplasty. Velocity provides clinically relevant physiological information in addition to angiography. Combining quantitative angiography, velocity measurements and laboratory data allow the calculation of blood flow, Reynold's numbers and shear stress, thereby providing complex fluid dynamic information. Thus the evaluation of haemo-dynamics in single and multiple obstructions before and after intervention is improved. Fluid dynamic parameters pre-and post-PTLA are significantly correlated with clinical short-term result.},
}

Adult
Aged
Aged, 80 and over
Angiography
*Angioplasty, Balloon, Laser-Assisted
Blood Flow Velocity
Blood Viscosity
Exercise Test
Female
Humans
Male
Middle Aged
Peripheral Vascular Diseases/diagnosis/*physiopathology/therapy
Ultrasonography, Interventional

@article {pmid9496765,
year = {1996},
author = {Hrncír, E},
title = {Flow resistance of airways under hyperbaric conditions.},
journal = {Physiological research},
volume = {45},
number = {2},
pages = {153-158},
pmid = {9496765},
issn = {0862-8408},
mesh = {*Air Pressure ; Airway Resistance/*physiology ; Gases ; Humans ; Models, Biological ; Trachea/anatomy & histology/physiology ; Viscosity ; },
abstract = {Based on the known relations governing flow resistance of a tube during laminar and turbulent flow and the value of the so-called Reynold's number the following conclusions were derived: 1. The flow resistance of airways increases under hyperbaric conditions because a) the turbulent flow participates in the airways to a greater extent due to its gradual extension to minor airways, and b) during turbulent flow the flow resistance is directly proportional to the pressure of the inhaled gas. 2. If the pressure in the surrounding environment increases n-times, this has an impact on the distribution of laminar and turbulent flow in the airways and their flow resistance, similarly as if the flow rates would increase n-times under normobaric conditions. 3. Dynamic indicators of lung ventilation corresponding to higher flow rates (e.g. PEF - peak expiratory flow) are reduced under hyperbaric conditions to a greater extent than the dynamic parameters corresponding to lower flow rates (e.g. FMEF25-75 - forced midexpiratory flow) determined usually by conditions in the minor airways, where the flow usually remains laminar or intermediate.},
}

*Air Pressure
Airway Resistance/*physiology
Gases
Humans
Models, Biological
Trachea/anatomy & histology/physiology
Viscosity

@article {pmid10878326,
year = {2000},
author = {Cammarn, SR and Sakr, A},
title = {Predicting dissolution via hydrodynamics: salicylic acid tablets in flow through cell dissolution.},
journal = {International journal of pharmaceutics},
volume = {201},
number = {2},
pages = {199-209},
doi = {10.1016/s0378-5173(00)00415-4},
pmid = {10878326},
issn = {0378-5173},
mesh = {Models, Theoretical ; Pharmacopoeias as Topic ; Salicylic Acid/administration & dosage/*chemistry ; Solubility ; Solvents ; Spectrophotometry, Ultraviolet ; Tablets ; United States ; },
abstract = {A model was established for the dissolution of non-disintegrating salicylic acid tablets as a function of hydrodynamic conditions in the Flow Through Cell system (USP Apparatus 4). The approach was to model the dissolution rate of the material as a function of the Reynold's number, the dimensionless engineering term that describes the degree of turbulence. The dissolution rate of USP calibrator salicylic acid tablets was measured as a function of tablet size, orientation within the cell, dissolution media flow rate, and cell size. All of these variables were found to have an effect on dissolution rate, consistent with theory. An equation to predict this dissolution was established as: N(SH)=-21.1+12.6xN(RE)(0.5), R(2)=0.99; 10 }

Models, Theoretical
Pharmacopoeias as Topic
Salicylic Acid/administration & dosage/*chemistry
Solubility
Solvents
Spectrophotometry, Ultraviolet
Tablets
United States

@article {pmid11522303,
year = {2001},
author = {Long, Q and Xu, XY and Ramnarine, KV and Hoskins, P},
title = {Numerical investigation of physiologically realistic pulsatile flow through arterial stenosis.},
journal = {Journal of biomechanics},
volume = {34},
number = {10},
pages = {1229-1242},
doi = {10.1016/s0021-9290(01)00100-2},
pmid = {11522303},
issn = {0021-9290},
mesh = {Arterial Occlusive Diseases/*physiopathology ; Blood Flow Velocity ; *Computer Simulation ; Humans ; *Models, Cardiovascular ; Pulsatile Flow/*physiology ; Stress, Mechanical ; },
abstract = {Numerical simulations of pulsatile blood flow in straight tube stenosis models were performed to investigate the poststenotic flow phenomena. In this study, three axisymmetrical and three asymmetrical stenosis models with area reduction of 25%, 50% and 75% were constructed. A measured human common carotid artery blood flow waveform was used as the upstream flow condition which has a mean Reynold's number of 300. All calculations were performed with high spatial and temporal resolutions. Flow features such as velocity profiles, flow separation zone (FSZ), and wall shear stress (WSS) distributions in the poststenotic region for all models are presented. The results have demonstrated that the formation and development of FSZs in the poststenotic region are very complex, especially in the flow deceleration phase. In axisymmetric stenoses the poststenotic flow is more sensitive to changes in the degree of stenosis than in asymmetric models. For severe stenoses, the stenosis influence length is shorter in asymmetrical models than in axisymmetrical cases. WSS oscillations (between positive and negative values) have been observed at various downstream locations in some models. The amplitude of the oscillation depends strongly on the axial location and the degree of stenosis.},
}

Arterial Occlusive Diseases/*physiopathology
Blood Flow Velocity
*Computer Simulation
Humans
*Models, Cardiovascular
Pulsatile Flow/*physiology
Stress, Mechanical

@article {pmid16883682,
year = {2006},
author = {Wu, Y and Ghaly, ES},
title = {Effect of hydrodynamic environment on tablet dissolution using flow-through dissolution apparatus.},
journal = {Puerto Rico health sciences journal},
volume = {25},
number = {1},
pages = {75-83},
pmid = {16883682},
issn = {0738-0658},
mesh = {Solubility ; *Tablets ; Water ; },
abstract = {The main objective of this research is to investigate the principles underlying the dissolution process, study the phenomena of drug release in laminar flow, and better understand the effect of hydrodynamic condition on drug dissolution, in order to predict drug dissolution from a solid dosage form. Two drug models were selected, theophylline (Class I) and naproxen (Class II), and were formulated into conventional tablets containing 105 mg theophylline or 300 mg naproxen using wet granulation method. Additionally theophylline (105 mg) and naproxen (300 mg) matrices containing 30% hydroxypropylmethylcellulose (HPMC) polymer were prepared by direct compression and tested for dissolution using both USP II and IV dissolution apparatus. Tablets were tested for dissolution (USP IV) using different cell diameter, flow rate, and different position of the tablet inside the cell. In general, the drug dissolution at a given time is a direct function of the flow rate, increasing the flow rate increases drug release. The use of a small cell resulted in faster drug dissolution and higher Reynold's Number than using a large cell. Tablet position in the cell, also has an effect on drug dissolution, inserting the tablet in a horizontal position inside the cell gave faster dissolution than a vertical position. The hydrodynamic conditions did not affect the drug dissolution from HPMC controlled release tablets indicating that the drug dissolution is controlled by the matrix. An equation to predict drug dissolution from conventional tablets was established: Sh=-21.36+10.58Re(1/2) where R2=0.98. This study demonstrated that hydrodynamic conditions, and type of dissolution testing apparatus used have an effect on dissolution rate, mass transfer rate, and film thickness underlying dissolution process.},
}

Solubility
*Tablets
Water

@article {pmid18273548,
year = {2008},
author = {Yamaguchi, R and Ujiie, H and Haida, S and Nakazawa, N and Hori, T},
title = {Velocity profile and wall shear stress of saccular aneurysms at the anterior communicating artery.},
journal = {Heart and vessels},
volume = {23},
number = {1},
pages = {60-66},
pmid = {18273548},
issn = {0910-8327},
mesh = {Blood Flow Velocity/*physiology ; Cerebrovascular Circulation/*physiology ; Humans ; Intracranial Aneurysm/*physiopathology ; Laser-Doppler Flowmetry ; Models, Theoretical ; Severity of Illness Index ; Shear Strength ; Stress, Mechanical ; },
abstract = {It has recently been shown that the aspect ratio (dome/neck) of an aneurysm correlates well with intraaneurysmal blood flow. Aneurysms with an aspect ratio larger than 1.6 carry a higher risk of rupture. We examined the effect of aspect ratio (AR) on intra-aneurysmal flow using experimental models. Flow visualization with particle imaging velocimetry and measurement of wall shear stress using laser Doppler anemometry were performed on three different aneurysm models: AR 0.5, 1.0, and 2.0. Intraaneurysmal flow consists of inflow, circulation, and outflow. Rapid inflow impinged on the distal neck creating a stagnant point. Rapid flow and maximum wall shear stress were observed in the vicinity of the stagnant point. By changing the Reynold's number, the stagnant point moved. By increasing the AR of the aneurysm, vortices inside the aneurysm sac closed and very slow flow was observed, resulting in very low shear stress markedly at a Reynold's number of 250, compatible with the diastolic phase. In the aneurysm model AR 2.0, both rapid flow at the neck and vortices inside the aneurysm are sufficient to activate platelets, making a thrombus that may anchor on the dome where very slow flow takes place. Hemodynamics in aneurysms larger than AR 2.0 definitely contribute to thrombus formation.},
}

Blood Flow Velocity/*physiology
Cerebrovascular Circulation/*physiology
Humans
Intracranial Aneurysm/*physiopathology
Laser-Doppler Flowmetry
Models, Theoretical
Severity of Illness Index
Shear Strength
Stress, Mechanical

@article {pmid18471808,
year = {2008},
author = {Jayalalitha, G and Shanthoshini Deviha, V and Uthayakumar, R},
title = {Fractal model for blood flow in cardiovascular system.},
journal = {Computers in biology and medicine},
volume = {38},
number = {6},
pages = {684-693},
doi = {10.1016/j.compbiomed.2008.03.002},
pmid = {18471808},
issn = {0010-4825},
mesh = {Algorithms ; Blood Flow Velocity/physiology ; Blood Pressure/physiology ; *Computer Simulation ; Coronary Circulation/*physiology ; Elasticity ; *Fractals ; Heart/anatomy & histology ; Humans ; Models, Anatomic ; *Models, Cardiovascular ; Vascular Resistance/physiology ; },
abstract = {Blood flow in the cardiovascular system is the central point of experimental and theoretical investigation. The objective of the study is to determine the blood flow in the cardiovascular system using Darcy's law, Reynold's number and Poiseuille's equation. A possible way of modeling of self-similar biological tree-like structure is proposed. Special attention is paid to the blood vessel system, with elaboration on a model with certain spatial arrangement of the vessels and reasonable dependence of the blood pressure on the vessels diameter such that the organism has a homogeneous oxygen supply. Flow analysis in the above systems is analyzed by invasion percolation. The blood flow in the cardiovascular system has been numerically calculated for both normal and abnormal patients. A new algorithm has been introduced to visit the blood vessels in a robust manner which avoids loops and provides us the results in a simple manner.},
}

Algorithms
Blood Flow Velocity/physiology
Blood Pressure/physiology
*Computer Simulation
Coronary Circulation/*physiology
Elasticity
*Fractals
Heart/anatomy & histology
Humans
Models, Anatomic
*Models, Cardiovascular
Vascular Resistance/physiology

@article {pmid21491262,
year = {2011},
author = {Nadeem, S and Akbar, NS and Hayat, T and Hendi, AA},
title = {Numerical and series solutions of the peristaltic motion of an Oldroyd 8-constant fluid in an endoscope.},
journal = {Computer methods in biomechanics and biomedical engineering},
volume = {14},
number = {11},
pages = {987-993},
doi = {10.1080/10255842.2010.503960},
pmid = {21491262},
issn = {1476-8259},
mesh = {*Endoscopes ; *Models, Theoretical ; *Peristalsis ; },
abstract = {In the present article, we have presented the peristaltic flow of an Oldroyd 8-constant fluid in an endoscope. The governing equations for the flow problem are simplified using long wavelength and low Reynold's number approximations. The solutions of the simplified problem are calculated using (i) Homotopy analysis method and (ii) Shooting method. The comparison of both the solutions shows a very good agreement between the results. The graphical results for the velocity field and stresses are presented to show the physical behaviour of all the parameters appearing in the problem.},
}

*Endoscopes
*Models, Theoretical
*Peristalsis

@article {pmid22538166,
year = {2012},
author = {Banerjee, S and Sutanto, S and Kleijn, JM and van Roosmalen, MJ and Witkamp, GJ and Stuart, MA},
title = {Colloidal interactions in liquid CO2--a dry-cleaning perspective.},
journal = {Advances in colloid and interface science},
volume = {175},
number = {},
pages = {11-24},
doi = {10.1016/j.cis.2012.03.005},
pmid = {22538166},
issn = {1873-3727},
mesh = {Carbon Dioxide/*chemistry ; *Clothing ; Colloids/chemistry ; Detergents/*chemistry ; Soil/analysis/chemistry ; Solvents/chemistry ; Surface-Active Agents/chemistry ; Tetrachloroethylene/*chemistry ; Water/chemistry ; },
abstract = {Liquid CO(2) is a viable alternative for the toxic and environmentally harmful solvents traditionally used in dry-cleaning industry. Although liquid CO(2) dry-cleaning is being applied already at a commercial scale, it is still a relatively young technique which poses many challenges. The focus of this review is on the causes of the existing problems and directions to solve them. After presenting an overview of the state-of-the-art, we analyze the detergency challenges from the fundamentals of colloid and interface science. The properties of liquid CO(2) such as dielectric constant, density, Hamaker constant, refractive index, viscosity and surface tension are presented and in the subsequent chapters their effects on CO(2) dry-cleaning operation are delineated. We show, based on theory, that the van der Waals forces between a model soil (silica) and model fabric (cellulose) through liquid CO(2) are much stronger compared to those across water or the traditional dry-cleaning solvent PERC (perchloroethylene). Prevention of soil particle redeposition in liquid CO(2) by electrostatic stabilization is challenging and the possibility of using electrolytes having large anionic parts is discussed. Furthermore, the role of different additives used in dry-cleaning, such as water, alcohol and surfactants, is reviewed. Water is not only used as an aid to remove polar soils, but also enhances adhesion between fabric and soil by forming capillary bridges. Its role as a minor component in liquid CO(2) is complex as it depends on many factors, such as the chemical nature of fabrics and soil, and also on the state of water itself, whether present as molecular solution in liquid CO(2) or phase separated droplets. The phenomena of wicking and wetting in liquid CO(2) systems are predicted from the Washburn-Lucas equation for fabrics of various surface energies and pore sizes. It is shown that nearly complete wetting is desirable for good detergency. The effect of mechanical action and fluid dynamic conditions on dry-cleaning is analyzed theoretically. From this it follows that in liquid CO(2) an order of magnitude higher Reynold's number is required to exceed the binding forces between fabric and soil as opposed to PERC or water, mainly due to the strong van der Waals forces and the low viscosity of CO(2) at dry-cleaning operational conditions.},
}

Carbon Dioxide/*chemistry
*Clothing
Colloids/chemistry
Detergents/*chemistry
Soil/analysis/chemistry
Solvents/chemistry
Surface-Active Agents/chemistry
Tetrachloroethylene/*chemistry
Water/chemistry

@article {pmid22779677,
year = {2012},
author = {Raghu, RC and Schofield, J},
title = {Simulation of tethered oligomers in nanochannels using multi-particle collision dynamics.},
journal = {The Journal of chemical physics},
volume = {137},
number = {1},
pages = {014901},
doi = {10.1063/1.4731662},
pmid = {22779677},
issn = {1089-7690},
abstract = {The effect of a high Reynold's number, pressure-driven flow of a compressible gas on the conformation of an oligomer tethered to the wall of a square channel is studied under both ideal solvent and poor solvent conditions using a hybrid multiparticle collision dynamics and molecular dynamics algorithm. Unlike previous studies, the flow field contains an elongational component in addition to a shear component as well as fluid slip near the walls and results in a Schmidt number for the polymer beads that is less than unity. In both solvent regimes the oligomer is found to extend in the direction of flow. Under the ideal solvent conditions, torsional twisting of the chain and aperiodic cyclical dynamics are observed for the end of the oligomer. Under poor solvent conditions, a metastable helix forms in the end of the chain despite the lack of any attractive potential between beads in the oligomeric chain. The formation of the helix is postulated to be the result of a solvent induced chain collapse that has been confined to a single dimension by a strong flow field.},
}

@article {pmid22852428,
year = {2012},
author = {Karadagli, F and Rittmann, BE and McAvoy, DC and Richardson, JE},
title = {Effect of turbulence on the disintegration rate of flushable consumer products.},
journal = {Water environment research : a research publication of the Water Environment Federation},
volume = {84},
number = {5},
pages = {424-433},
doi = {10.2175/106143012x13354606450960},
pmid = {22852428},
issn = {1061-4303},
mesh = {*Environmental Restoration and Remediation ; *Household Products ; Hydrodynamics ; *Waste Disposal, Fluid ; },
abstract = {A previously developed model for the physical disintegration of flushable consumer products is expanded by investigating the effects of turbulence on the rate of physical disintegration. Disintegration experiments were conducted with cardboard tampon applicators at 100, 150, and 200 rotations per minute, corresponding to Reynold's numbers of 25,900, 39,400, and 52,900, respectively, which were estimated by using computational fluid dynamics modeling. The experiments were simulated with the disintegration model to obtain best-fit values of the kinetic and distribution parameters. Computed rate coefficients (ki) for all solid sizes (i.e., greater than 8, 4 to 8, 2 to 4, and 1 to 2 mm) increased strongly with Reynold's number or rotational speed. Thus, turbulence strongly affected the disintegration rate of flushable products, and the relationship of the ki values to Reynold's number can be included in mathematical representations of physical disintegration.},
}

*Environmental Restoration and Remediation
*Household Products
Hydrodynamics
*Waste Disposal, Fluid

@article {pmid23325520,
year = {2014},
author = {Nocke, H and Meyer, F and Lessmann, V},
title = {[Aspects of vascular physiology in clinical and vascular surgical practice: basic principles of vascular mechanics].},
journal = {Zentralblatt fur Chirurgie},
volume = {139},
number = {5},
pages = {499-507},
doi = {10.1055/s-0032-1327967},
pmid = {23325520},
issn = {1438-9592},
mesh = {Blood Pressure/*physiology ; Cardiovascular Diseases/*physiopathology/*surgery ; *Cardiovascular Physiological Phenomena ; Hemodynamics/*physiology ; Humans ; Models, Cardiovascular ; Muscle, Smooth, Vascular/*physiopathology ; Pulsatile Flow/*physiology ; Reference Values ; Vascular Stiffness/*physiology ; },
abstract = {To be able to evaluate properly a vascular problem, basic concepts of vascular physiology need to be considered, as they have been taught in physiology for a long time. This article deals with selected definitions and laws of passive vascular mechanics, subdivided into parameters of vascular filling and parameters of vascular flow. PARAMETERS OF VASCULAR FILLING: During vascular filling the transmural pressure distends the vascular wall until it is balanced by the wall tension. The extent of this distension up to the point of balance depends on the elasticity of the wall. Transmural pressure, wall tension and elasticity are defined, and their respective importance is described by clinical examples, e.g. aneurysm and varix. PARAMETERS OF VASCULAR FLOW: The vascular flow can be divided into stationary and pulsating components. Both components are relevant for the bloodstream. Since the blood flow is directed in the circuit, it can be understood in first approximation as stationary ("direct current").The direct current model uses only the average values of the pulsating variables. The great advantage of the direct current model is that it can be described with simple laws, which are not valid without reservation, but often allow a first theoretical approach to a vascular problem: Ohm's law, driving pressure, flow resistance, Hagen-Poiseuille law, wall shear stress, law of continuity, Bernoulli's equation and Reynold's number are described and associated with clinical examples.The heart is a pressure-suction pump and produces a pulsating flow, the pulse. The pulse runs with pulse wave velocity, which is much larger than the blood flow velocity, through the arterial vascular system. During propagation, the pulse has to overcome the wave resistance (impedance). Wherever the wave resistance changes, e.g., at vascular bifurcations and in the periphery, it comes to reflections. The incident (forward) and reflected (backward) waves are superimposed to yield the resulting pulse wave. This pulse wave allows one to distinguish pressure and flow pulse by measurement. Both are described separately, and their respective clinical meaning is illustrated by appropriate examples, e.g., arterial stiffness and pre-/postocclusive high/low resistance flow, respectively.},
}

Blood Pressure/*physiology
Cardiovascular Diseases/*physiopathology/*surgery
*Cardiovascular Physiological Phenomena
Hemodynamics/*physiology
Humans
Models, Cardiovascular
Muscle, Smooth, Vascular/*physiopathology
Pulsatile Flow/*physiology
Reference Values
Vascular Stiffness/*physiology

@article {pmid24973405,
year = {2014},
author = {Rembold, CM and Suratt, PM},
title = {Airway turbulence and changes in upper airway hydraulic diameter can be estimated from the intensity of high frequency inspiratory sounds in sleeping adults.},
journal = {The Journal of physiology},
volume = {592},
number = {17},
pages = {3831-3839},
pmid = {24973405},
issn = {1469-7793},
support = {M01 RR00847/RR/NCRR NIH HHS/United States ; },
mesh = {Adult ; Humans ; *Inhalation ; Larynx/pathology/*physiopathology ; Models, Biological ; Nose/pathology/*physiopathology ; Sleep Apnea, Obstructive/pathology/*physiopathology ; *Snoring ; },
abstract = {Obstructive sleep disordered breathing can cause death and significant morbidity in adults and children. We previously found that children with smaller upper airways (measured by magnetic resonance imaging while awake) generated loud high frequency inspiratory sounds (HFIS, defined as inspiratory sounds > 2 kHz) while they slept. The purpose of this study was (1) to determine what characteristics of airflow predicted HFIS intensity, and (b) to determine if we could calculate changes in hydraulic diameter (D) in both an in vitro model and in the upper airways of sleeping humans. In an in vitro model, high frequency sound intensity was an estimate of airflow turbulence as reflected by the Reynold's number (Re). D of the in vitro model was calculated using Re, the pressure gradient, Swamee-Jain formula and Darcy formula. D was proportional to but smaller than the actual diameters (r(2) = 0.94). In humans, we measured HFIS intensity and the pressure gradient across the upper airway (estimated with oesophageal pressure, Pes) during polysomnography in four adult volunteers and applied the same formulae to calculate D. At apnoea termination when the airway opens, we observed (1) an increase in HFIS intensity suggesting an increase in turbulence (higher Re), and (2) a larger calculated D. This method allows dynamic estimation of changes in relative upper airway hydraulic diameter (D) in sleeping humans with narrowed upper airways.},
}

Adult
Humans
*Inhalation
Larynx/pathology/*physiopathology
Models, Biological
Nose/pathology/*physiopathology
Sleep Apnea, Obstructive/pathology/*physiopathology
*Snoring

@article {pmid25533171,
year = {2014},
author = {Astumian, RD},
title = {Enhanced diffusion, chemotaxis, and pumping by active enzymes: progress toward an organizing principle of molecular machines.},
journal = {ACS nano},
volume = {8},
number = {12},
pages = {11917-11924},
doi = {10.1021/nn507039b},
pmid = {25533171},
issn = {1936-086X},
mesh = {*Chemotaxis ; Enzymes/*isolation & purification ; *Microfluidic Analytical Techniques ; },
abstract = {Active enzymes diffuse more rapidly than inactive enzymes. This phenomenon may be due to catalysis-driven conformational changes that result in "swimming" through the aqueous solution. Recent additional work has demonstrated that active enzymes can undergo chemotaxis toward regions of high substrate concentration, whereas inactive enzymes do not, and, further, that active enzymes immobilized at surfaces can directionally pump liquids. In this Perspective, I will discuss these phenomena in light of Purcell's work on directed motion at low Reynold's number and in the context of microscopic reversibility. The conclusions suggest that a deep understanding of catalytically driven enhanced diffusion of enzymes and related phenomena can lead toward a general organizing principle for the design, characterization, and operation of molecular machines.},
}

*Chemotaxis
Enzymes/*isolation & purification
*Microfluidic Analytical Techniques

@article {pmid27480731,
year = {2016},
author = {Akbar, NS and Butt, AW},
title = {Bio mathematical venture for the metallic nanoparticles due to ciliary motion.},
journal = {Computer methods and programs in biomedicine},
volume = {134},
number = {},
pages = {43-51},
doi = {10.1016/j.cmpb.2016.06.002},
pmid = {27480731},
issn = {1872-7565},
mesh = {Cilia/*physiology ; Computer Graphics ; Metal Nanoparticles/*chemistry ; *Models, Theoretical ; },
abstract = {BACKGROUND AND OBJECTIVES: The present investigation is associated with the contemporary study of viscous flow in a vertical tube with ciliary motion.

METHODS/RESULTS/CONCLUSIONS: The main flow problem has been modeled using cylindrical coordinates; flow equations are simplified to ordinary differential equations using longwave length and low Reynold's number approximation; and exact solutions have been obtained for velocity, pressure gradient and temperature. Results acquired are discussed graphically for better understanding. Streamlines for the velocity profile are plotted to discuss the trapping phenomenon. It is seen that with an increment in the Grashof number, the velocity of the governing fluids starts to decrease significantly.},
}

Cilia/*physiology
Computer Graphics
Metal Nanoparticles/*chemistry
*Models, Theoretical

@article {pmid28505761,
year = {2017},
author = {Pride, SR and Vasco, DW and Flekkoy, EG and Holtzman, R},
title = {Dispersive transport and symmetry of the dispersion tensor in porous media.},
journal = {Physical review. E},
volume = {95},
number = {4-1},
pages = {043103},
doi = {10.1103/PhysRevE.95.043103},
pmid = {28505761},
issn = {2470-0053},
abstract = {The macroscopic laws controlling the advection and diffusion of solute at the scale of the porous continuum are derived in a general manner that does not place limitations on the geometry and time evolution of the pore space. Special focus is given to the definition and symmetry of the dispersion tensor that is controlling how a solute plume spreads out. We show that the dispersion tensor is not symmetric and that the asymmetry derives from the advective derivative in the pore-scale advection-diffusion equation. When flow is spatially variable across a voxel, such as in the presence of a permeability gradient, the amount of asymmetry can be large. As first shown by Auriault [J.-L. Auriault et al. Transp. Porous Med. 85, 771 (2010)TPMEEI0169-391310.1007/s11242-010-9591-y] in the limit of low Péclet number, we show that at any Péclet number, the dispersion tensor D_{ij}
satisfies the flow-reversal symmetry D_{ij}(
+q)=D_{ji}(
-q) where q is the mean flow in the voxel under analysis; however, Reynold's number must be sufficiently small that the flow is reversible when the force driving the flow changes sign. We also demonstrate these symmetries using lattice-Boltzmann simulations and discuss some subtle aspects of how to measure the dispersion tensor numerically. In particular, the numerical experiments demonstrate that the off-diagonal components of the dispersion tensor are antisymmetric which is consistent with the analytical dependence on the average flow gradients that we propose for these off-diagonal components.},
}

@article {pmid30009583,
year = {2017},
author = {Malviya, R and Sharma, P and Dubey, S},
title = {Kheri (Acacia chundra, family: Mimosaceae) gum: Characterization using analytical, mathematical and pharmaceutical approaches.},
journal = {Polimery w medycynie},
volume = {47},
number = {2},
pages = {65-76},
doi = {10.17219/pim/76515},
pmid = {30009583},
issn = {0370-0747},
mesh = {Acacia/*chemistry ; Excipients ; Particle Size ; Plant Gums/*chemistry/isolation & purification ; Polysaccharides/chemistry ; Rheology ; Spectroscopy, Fourier Transform Infrared ; Viscosity ; },
abstract = {BACKGROUND: Natural polymers have been used in medical, pharmaceutical, cosmetic and food industry. They should be characterized before their possible applications in different industries.

OBJECTIVES: The objective of this study was to characterize Kheri (Acacia chundra, family: Mimosaceae) gum using analytical, mathematical and pharmaceutical approaches.

MATERIAL AND METHODS: Crude Kheri gum (KG) was purified using distilled water as a solvent and ethanol as a precipitating agent. KG was characterized in terms of phytochemical screening, micromeritic properties, microbial load, ash value, rheological behavior, solid state 1H nuclear magnetic resonance (NMR), mass spectra and Fourier-transform infrared spectroscopy (FTIR) studies for their possible applications in food, cosmetics and pharmaceutical industry.

RESULTS: Studies show that KG contains carbohydrates, while protein, fat, volatile oils, alkaloids and glycosides are absent. 1% aqueous solution of polysaccharide showed 25.58 × 103 kJ/kg activation energy and 1.39 Reynold's number. Viscosity average molecular weight of purified gum was found 1.73 × 105 D. Thermodynamic parameters, i.e., change in enthalpy ΔHv and change in enthalpy ΔHv, were found to be 12.26 × 103 kJ/mol and 24.47 kJ/mol, respectively. Mathematical approach also determined the rod shaped conformation of KG in aqueous solution. IR spectroscopic study shows the presence of free (COO-) and esterified (COO-R) carboxylic acid, ether (C-O stretching), galacturonic acid and mannose in polysaccharide 1H NMR study predicts presence of tetrahydropyran hydrogen in molecule. Furthermore, KG was also characterized as a suspending agent using paracetamol as a model drug. Flow rate, pH, particle size and settling behavior of suspensions were evaluated. Initial particle size of dispersed phase particles does not change significantly after 45 days.

CONCLUSIONS: From the findings of the research it can be concluded that KG can be used as an excipient in cosmaceuticals and pharmaceuticals and its characteristic rheological behavior may attract rheologists.},
}

Acacia/*chemistry
Excipients
Particle Size
Plant Gums/*chemistry/isolation & purification
Polysaccharides/chemistry
Rheology
Spectroscopy, Fourier Transform Infrared
Viscosity

@article {pmid30761361,
year = {2018},
author = {Shah, RA and Khan, A and Shuaib, M},
title = {On the study of flow between unsteady squeezing rotating discs with cross diffusion effects under the influence of variable magnetic field.},
journal = {Heliyon},
volume = {4},
number = {11},
pages = {e00925},
pmid = {30761361},
issn = {2405-8440},
abstract = {The aim of this article is to provide an analytical and numerical investigation to the viscous fluid flow, heat and mass transfer under the influence of a variable magnetic field. The governing system of partial differential equations are transformed by means of similarity transformations to a system of ordinary differential equations which are solved by Homotopy Analysis Method (HAM) and BVP4c. The effects of involved physical parameters are illustrated for the velocity components, magnetic field components, heat and mass transfers. Authentification of HAM results for various involved physical parameters are supported by comparison with numerical results obtained by BVP4c. It is observed that increasing distance between discs increase pressure on lower disc and torque on upper disc. It is also observed that increase in axial component of magnetic field increase fluid's axial velocity and increase in magnetic Reynold's number decrease magnetic flux it lower disc. Heat flux from lower to upper disc is increased by increase in Dufour number.},
}

@article {pmid30985778,
year = {2019},
author = {Occhicone, A and Sinibaldi, A and Sonntag, F and Munzert, P and Danz, N and Michelotti, F},
title = {Study of fluid dynamics at the boundary wall of a microchannel by Bloch surface waves.},
journal = {Optics letters},
volume = {44},
number = {8},
pages = {1932-1935},
doi = {10.1364/OL.44.001932},
pmid = {30985778},
issn = {1539-4794},
abstract = {Understanding how a fluid flows at the boundaries when it is confined at the microscale/nanoscale is crucial for a broad range of engineering and biology applications. We propose an experimental technique based on Bloch surface waves sustained by a one-dimensional photonic crystal to evaluate the speed of the contact line, i.e., the triple junction separating three phases, in the low Reynold's number regime, and with a nanometric resolution. Here, we report on the experimental characterization of the translatory motion of the contact line that separates two water solutions with a relatively high refractive index mismatch (7.35×10[-3]) and its slipping over a solid surface. The advantages are the relative simplicity and economy of the experimental configuration.},
}

@article {pmid33907644,
year = {2021},
author = {Kesserwani, H},
title = {Space Flight-Associated Neuroocular Syndrome, Idiopathic Intracranial Hypertension, and Pseudotumor Cerebri: Phenotypic Descriptions, Pathogenesis, and Hydrodynamics.},
journal = {Cureus},
volume = {13},
number = {3},
pages = {e14103},
pmid = {33907644},
issn = {2168-8184},
abstract = {Recent data from astronauts who have returned to Earth from a long-duration space flight have unequivocally distinguished spaceflight-associated neuro-ocular syndrome (SANS) from idiopathic intracranial hypertension (IIH) and pseudotumor cerebri (PTC). We review the semiology and pathogenesis of these three entities, noting that optic disc edema is what unites them, and this where the similarities between SANS and IIH/PTC end. We distinguish between PTC and IIH and between SANS and IIH/PTC and review the medical and surgical therapy of IIH/PTC. The key to understanding the phenomenon of optic disc edema is the geometry of the optic nerve sheath, which is a simulacrum of an inverted Venturi tube. This allows us to theoretically study the hydrodynamics of the optic nerve sheath by applying simple physical laws, including the Venturi effect, Poiseuille's law, and Reynold's number, and we speculate on nature's design and the correlation of form and function in understanding how cerebrospinal fluid (CSF) circulates in the optic nerve sheath as it approaches the optic nerve head. Recent spectacular data on the histology of the blood nerve-barrier of the optic nerve disc and the glymphatic system of the optic nerve sheath will also help us understand the development of optic disc edema due to the microgravity-induced cephalad shift of CSF in SANS. We will explore the role of the sodium/potassium adenosine triphosphatase (ATPase) pump on choroid plexus epithelial cells and the aquaporin-4 water receptors located on astrocyte end-feet and their complex interactions with the tetracyclines, mineralocorticoids, and therapeutic agents with carbonic anhydrase activity. We also adumbrate the complex interactions between obesity, vitamin A, and 11-beta-hydroxysteroid dehydrogenase and how the aquaporin-4 receptor relates to these interactions.},
}

@article {pmid35343677,
year = {2022},
author = {Chen, H and Li, Y and Wang, Y and Ning, P and Shen, Y and Wei, X and Feng, Q and Liu, Y and Li, Z and Xu, C and Huang, S and Deng, C and Wang, P and Cheng, Y},
title = {An Engineered Bacteria-Hybrid Microrobot with the Magnetothermal Bioswitch for Remotely Collective Perception and Imaging-Guided Cancer Treatment.},
journal = {ACS nano},
volume = {16},
number = {4},
pages = {6118-6133},
doi = {10.1021/acsnano.1c11601},
pmid = {35343677},
issn = {1936-086X},
mesh = {Humans ; Bacteria ; Hypoxia ; *Neoplasms/diagnostic imaging/drug therapy ; Perception ; },
abstract = {Microrobots driven by multiple propelling forces hold great potential for noninvasively targeted delivery in the physiologic environment. However, the remotely collective perception and precise propelling in a low Reynold's number bioenvironment remain the major challenges of microrobots to achieve desired therapeutic effects in vivo. Here, we reported a biohybrid microrobot that integrated with magnetic, thermal, and hypoxia sensitivities and an internal fluorescent protein as the dual reporter of thermal and positioning signals for targeted cancer treatment. There were three key elements in the microrobotic system, including the magnetic nanoparticle (MNP)-loaded probiotic Escherichia coli Nissle1917 (EcN@MNP) for spatially magnetic and hypoxia perception, a thermal-logic circuit engineered into the bacteria to control the biosynthesis of mCherry as the temperature and positioning reporter, and NDH-2 enzyme encoded in the EcN for enhanced anticancer therapy. According to the fluorescent-protein-based imaging feedback, the microrobot showed good thermal sensitivity and active targeting ability to the tumor area in a collective manner under the magnetic field. The cancer cell apoptosis was efficiently triggered in vitro and in vivo by the hybrid microrobot coupled with the effects of magnetothermal ablation and NDH-2-induced reactive oxygen species (ROS) damage. Our study demonstrates that the biohybrid EcN microrobot is an ideal platform to integrate the physical, biological, and chemical properties for collective perception and propelling in targeted cancer treatment.},
}

Humans
Bacteria
Hypoxia
*Neoplasms/diagnostic imaging/drug therapy
Perception

@article {pmid35620608,
year = {2022},
author = {Montalvo, S and Gomez, M and Lozano, A and Arias, S and Rodriguez, L and Morales-Acuna, F and Gurovich, AN},
title = {Differences in Blood Flow Patterns and Endothelial Shear Stress at the Carotid Artery Using Different Exercise Modalities and Intensities.},
journal = {Frontiers in physiology},
volume = {13},
number = {},
pages = {857816},
pmid = {35620608},
issn = {1664-042X},
support = {SC2 GM140952/GM/NIGMS NIH HHS/United States ; },
abstract = {Endothelial dysfunction is the first pathophysiological step of atherosclerosis, which is responsible for 90% of strokes. Exercise programs aim to reduce the risk of developing stroke; however, the majority of the beneficial factors of exercise are still unknown. Endothelial shear stress (ESS) is associated with endothelial homeostasis. Unfortunately, ESS has not been characterized during different exercise modalities and intensities in the carotid artery. Therefore, the purpose of this study was to determine exercise-induced blood flow patterns in the carotid artery. Fourteen apparently healthy young adults (males = 7, females = 7) were recruited for this repeated measures study design. Participants completed maximal oxygen consumption (VO2max) tests on a Treadmill, Cycle-ergometer, and Arm-ergometer, and 1-repetition maximum (1RM) tests of the Squat, Bench Press (Bench), and Biceps Curl (Biceps) on separate days. Thereafter, participants performed each exercise at 3 different exercise intensities (low, moderate, high) while a real-time ultrasound image and blood flow of the carotid artery was obtained. Blood flow patterns were assessed by estimating ESS via Womersley's estimation and turbulence via Reynold's number (Re). Data were analyzed using a linear mixed-effects model. Pairwise comparisons with Holm-Bonferroni correction were conducted with Hedge's g effect size to determine the magnitude of the difference. There was a main effect of intensity, exercise modality, and intensity * exercise modality interaction on both ESS (p < 0.001). Treadmill at a high intensity yielded the greatest ESS when compared to the other exercise modalities and intensities, while Bench Press and Biceps curls yielded the least ESS. All exercise intensities across all modalities resulted in turbulent blood flow. Clinicians must take into consideration how different exercise modalities and intensities affect ESS and Re of the carotid artery.},
}

@article {pmid35672348,
year = {2022},
author = {Saadoon, ZH and Ali, FH and Hamzah, HK and Abed, AM and Hatami, M},
title = {Improving the performance of mini-channel heat sink by using wavy channel and different types of nanofluids.},
journal = {Scientific reports},
volume = {12},
number = {1},
pages = {9402},
pmid = {35672348},
issn = {2045-2322},
abstract = {The combination of nano fluid and changing cross-section mini-channel heat sink effects have become a remarkable choice for the use of thermal devices such as miniature electronic devices to be effectively cooled. In this paper, the comparison of three dimensional straight and wavy channel configuration with using different types nano fluids are numerically investigated. The effects of wave amplitude and A particular type of volume fraction of (Copper Oxide CuO, Dimond Al2O3, Iron Oxide Fe3O4, Titanium Oxide TiO2 and Silver Ag-nano fluids are offered. Three amplitudes of waves (0.15 mm, 0.2 mm and 0.25 mm) and Reynold's number from 200 to 1000 and concentration volume varieties from 0 to 0.075 are used. The effect on thermal resistance, pressures drop, factor of friction of the mini channel is displayed. It is observed that the mini-channel sink's heat transfer efficiency is greatly enhanced compared to the straight channel in an event of adding distilled water as accoolant. The results indicate that nano fluid and wavy mini-channel can boost the heat sink's hydrothermal efficiency and Ag- water nano fluid in term of heat transfer, it outperforms other nanofluids an enhancement in the Nusselt number reached to 54% at concentration volume 0.075.},
}

@article {pmid35853555,
year = {2022},
author = {Kumar, M and Panneerselvam, E and Prabhu, K and Ganesh, SK and Vb, KKR},
title = {Prospective cohort study on short-term evaluation of septoplasty as early management of naso-septal fractures - A correlation of clinical outcomes with computational fluid dynamic parameters.},
journal = {Journal of stomatology, oral and maxillofacial surgery},
volume = {123},
number = {6},
pages = {639-644},
doi = {10.1016/j.jormas.2022.07.010},
pmid = {35853555},
issn = {2468-7855},
mesh = {Humans ; *Nasal Obstruction/diagnosis/etiology/surgery ; Nasal Septum/surgery ; Prospective Studies ; Hydrodynamics ; Pain ; },
abstract = {PURPOSE: Post-traumatic deviated nasal septum (PTDNS) leads to impaired breathing and poor esthetics. The aim of this study was to assess treatment outcomes of early septoplasty for correction of PTDNS and correlate it with computational fluid dynamic (CFD) parameters.

METHODS: This prospective cohort study included patients who underwent early septoplasty for PTDNS. Outcome variables were clinical (pain, nasal symmetry, and nasal obstruction) and computational (velocity, pressure, wall shear stress and Reynold's number). The cohort consisted of two groups: patients with history of closed reduction for nasal fractures (CR) and patients without (NCR). The primary outcome measure was response to treatment. Correlation between clinical and computational parameters, and influence of closed reduction on septoplasty outcomes were the secondary and tertiary outcomes, respectively. Descriptive and inferential statistics were performed to analyze data. Level of significance was fixed at 5% (α = 0.05).

RESULTS: The sample included 12 patients, of which 5 underwent CFD analysis. Pain score reduced from a pre-operative mean of 7.3 to 0.5 post-operatively (p<0.001). All patients demonstrated reduction of nasal obstruction (p<0.001) and deviation (p<0.001) post-operatively. CFD analysis revealed post-operative reduction of velocity (p = 0.005) and Reynold's number (p = 0.007), with positive correlation between nasal obstruction and CFD parameters. Though patients in the CR group demonstrated reduced nasal deviation and obstruction before septoplasty, as compared to the NCR group, their outcomes were comparable following septoplasty.

CONCLUSION: Early septoplasty improves functional and esthetic outcomes in patients with PTDNS. CFD simulation is a predictable method to objectively evaluate nasal function.},
}

Humans
*Nasal Obstruction/diagnosis/etiology/surgery
Nasal Septum/surgery
Prospective Studies
Hydrodynamics
Pain

@article {pmid36463256,
year = {2022},
author = {Zhu, F and Cheng, J},
title = {Comparison of the effects of litter decomposition process on soil erosion under simulated rainfall.},
journal = {Scientific reports},
volume = {12},
number = {1},
pages = {20929},
pmid = {36463256},
issn = {2045-2322},
mesh = {*Soil Erosion ; Soil ; Forests ; *Pinus ; Plant Leaves ; },
abstract = {Overland flow parameters play a pivotal role in soil erosion, which are affected by litter cover in forests. In this study, the litter layer of Pinus massoniana (Masson pine) was divided into non-decomposed and semi-decomposed layers. Seven litter coverage mass gradients, two slopes (5° and 10°), and two rainfall intensities (60 and 120 mm·h[-1]) were used for a systematic study of the effects of litter layer changes on overland flow dynamic characteristics. The objectives of this study were to explore the soil erosion process in litter different decomposition stages; to explore various relationships between hydraulic variables and litter characteristics. In the process of litter decomposition, overland flow patterns changed from transitional flow to laminar flow and from rapid flow to slow flow. The semi-decomposed layer's Reynold's number (Re), resistance coefficient (f), and soil separation rate ([Formula: see text]) were lower than that of the non-decomposed layer under the same conditions. Litter coverage, runoff and the diameter of the litter were major parameters that affected the Re, f, Fr, and Dr. Shrubs with wide leaves should be selected for understory vegetation replanting. The results of this study are helpful to understand the mechanisms of litter influencing erosion processes in different decomposition stages.},
}

*Soil Erosion
Soil
Forests
*Pinus
Plant Leaves

@article {pmid37101581,
year = {2022},
author = {Sun, R and Yu, P and Zuo, P and Alvarez, PJJ},
title = {Bacterial Concentrations and Water Turbulence Influence the Importance of Conjugation Versus Phage-Mediated Antibiotic Resistance Gene Transfer in Suspended Growth Systems.},
journal = {ACS environmental Au},
volume = {2},
number = {2},
pages = {156-165},
pmid = {37101581},
issn = {2694-2518},
abstract = {Despite the abundance of phage-borne antibiotic resistance genes (ARGs) in the environment, the frequency of ARG propagation via phage-mediated transduction (relative to via conjugation) is poorly understood. We investigated the influence of bacterial concentration and water turbulence level [quantified as Reynold's number (Re)] in suspended growth systems on the frequency of ARG transfer by two mechanisms: delivery by a lysogenic phage (phage λ carrying gentamycin-resistance gene, genR) and conjugation mediated by the self-transmissible plasmid RP4. Using Escherichia coli (E. coli) as the recipient, phage delivery had a comparable frequency (1.2 ± 0.9 × 10[-6]) to that of conjugation (1.1 ± 0.9 × 10[-6]) in suspensions with low cell concentration (10[4] CFU/mL) and moderate turbulence (Re = 5 × 10[4]). Turbulence affected cell (or phage)-to-cell contact rates and detachment (due to shear force), and thus, it affected the relative importance of conjugation versus phage delivery. At 10[7] CFU/mL, no significant difference was observed between the frequencies of ARG transfer by the two mechanisms under quiescent water conditions (2.8 ± 0.3 × 10[-5] for conjugation vs 2.2 ± 0.5 × 10[-5] for phage delivery, p = 0.19) or when Re reached 5 × 10[5] (3.4 ± 1.5 × 10[-5] for conjugation vs 2.9 ± 1.0 × 10[-5] for phage delivery, p = 0.52). Transcriptomic analysis of genes related to conjugation and phage delivery and simulation of cell (or phage)-to-cell collisions at different Re values corroborate that the importance of phage delivery relative to conjugation increases under either quiescent or turbulent conditions. This finding challenges the prevailing view that conjugation is the dominant ARG transfer mechanism and underscores the need to consider and mitigate potential ARG dissemination via transduction.},
}

@article {pmid37512786,
year = {2023},
author = {Tahir, MT and Anwar, S and Ahmad, N and Sattar, M and Qazi, UW and Ghafoor, U and Bhutta, MR},
title = {Thermal Management of Microelectronic Devices Using Nanofluid with Metal foam Heat Sink.},
journal = {Micromachines},
volume = {14},
number = {7},
pages = {},
pmid = {37512786},
issn = {2072-666X},
support = {2020R1G1A1012741//National Research Foundation of Korea/ ; },
abstract = {Microelectronic components are used in a variety of applications that range from processing units to smart devices. These components are prone to malfunctions at high temperatures exceeding 373 K in the form of heat dissipation. To resolve this issue, in microelectronic components, a cooling system is required. This issue can be better dealt with by using a combination of metal foam, heat sinks, and nanofluids. This study investigates the effect of using a rectangular-finned heat sink integrated with metal foam between the fins, and different water-based nanofluids as the working fluid for cooling purposes. A 3D numerical model of the metal foam with a BCC-unit cell structure is used. Various parameters are analyzed: temperature, pressure drop, overall heat transfer coefficient, Nusselt number, and flow rate. Fluid flows through the metal foam in a turbulent flow with a Reynold's number ranging from 2100 to 6500. The optimum fin height, thickness, spacing, and base thickness for the heat sink are analyzed, and for the metal foam, the material, porosity, and pore density are investigated. In addition, the volume fraction, nanoparticle material, and flow rate for the nanofluid is obtained. The results showed that the use of metal foam enhanced the thermal performance of the heat sink, and nanofluids provided better thermal management than pure water. For both cases, a higher Nusselt number, overall heat transfer coefficient, and better temperature reduction is achieved. CuO nanofluid and high-porosity low-pore-density metal foam provided the optimum results, namely a base temperature of 314 K, compared to 341 K, with a pressure drop of 130 Pa. A trade-off was achieved between the temperature reduction and pumping power, as higher concentrations of nanofluid provided better thermal management and resulted in a large pressure drop.},
}

@article {pmid42796187,
year = {2026},
author = {Wang, K and Li, J and Wang, L and Zhang, S and Zheng, X and Zheng, Q and Cui, H},
title = {Collective Motion and Programmable Self-Organization of Rotating Active Particles Manipulated by Magnetic Fields.},
journal = {Micromachines},
volume = {17},
number = {9},
pages = {},
doi = {10.3390/mi17091068},
pmid = {42796187},
issn = {2072-666X},
support = {2022YFF0503504//National Key Research and Development Program of China/ ; XDB0620102//Chinese Academy of Sciences/ ; XDA0470203//Chinese Academy of Sciences/ ; 12302357//National Natural Science Foundation of China/ ; 12472273//National Natural Science Foundation of China/ ; 2024JC-YBMS-020//Natural Science Foundation of Shaanxi Province/ ; 2024JC-YBMS-442//Natural Science Foundation of Shaanxi Province/ ; 2024151//Zhongke Technology Achievement Transfer and Transformation Center of Henan Province/ ; },
abstract = {Rotating magnetic microparticles are classic active matter systems dominated by competing magnetic dipolar attraction and spin-induced hydrodynamic repulsion, whose collective behaviors under programmable magnetic field remain insufficiently characterized. This work builds a two-dimensional orthogonal Helmholtz coil experimental setup to investigate the collective motion and self-organization of magnetic microparticles. For single-component assemblies, the hexatic order parameter varies non-monotonically with driving frequency and particle area fraction; an intermediate frequency range (60-80 Hz) yields optimal hexagonally ordered structures, and a full phase diagram covering clustered, ordered and disordered states is established. Binary mixtures of 200 μm and 300 μm particles display hydrodynamic driven size segregation, with the segregation parameter peaking uniformly at 60 Hz. By applying programmable Lissajous-type magnetic fields with mismatched orthogonal frequencies, we achieve tunable elliptical particle trajectories and controlled splitting of particle clusters. This study reveals the coupling mechanism between magnetic and finite Reynolds number hydrodynamic interactions and proposes a programmable method to dynamically reconfigure active microparticle swarms.},
}

@article {pmid42796201,
year = {2026},
author = {Yang, L and Hang, Y and Liu, R and Jiang, Q and Li, Z and Hong, J and Wu, Y},
title = {Controlling the Mixing Performance of Passive Micromixers with Variable Section Units.},
journal = {Micromachines},
volume = {17},
number = {9},
pages = {},
doi = {10.3390/mi17091082},
pmid = {42796201},
issn = {2072-666X},
abstract = {Changing the structures of microchannels has become an effective strategy for improving the mixing performance of passive micromixers. In this study, we propose a novel micromixer with variable section units through changing the geometric parameters including the type, the position, the number, and the ratio of the variable section units. The effects of these geometric parameters on the mixing performance were numerically investigated and parametrically compared. The results showed that the type of Gra channel, the initial position, a number of 4, and the ratio of 1:4 should be selected. With this selected configuration, the mixing efficiency of the micromixer can be significantly enhanced, with the mixing index exceeding 0.96 at a Reynolds number of 100. These findings demonstrate an effective design strategy for developing passive micromixers.},
}

@article {pmid42790497,
year = {2026},
author = {Wind-Hansen, M and Godefroid, M and Kalinichev, A and Behrendt, L and Ahmerkamp, S and Koren, K},
title = {Flash nanoprecipitation of monodisperse luminescent nanosensors for simultaneous oxygen and flow imaging.},
journal = {Methods and applications in fluorescence},
volume = {},
number = {},
pages = {},
doi = {10.1088/2050-6120/aeac9c},
pmid = {42790497},
issn = {2050-6120},
abstract = {Understanding mass transfer in aquatic biological systems requires simultaneous measurements of velocity fields and transported scalar fields. Such scalar fields, including spatial distributions of dissolved oxygen concentration, can be measured using luminescent sensor particles that also function as flow tracers, but their performance is affected by particle size and dispersity. Therefore, reproducible preparation of monodisperse sensor particles is essential for reliable sensing and velocimetry. Here, we systematically optimized flash nanoprecipitation to prepare oxygen-sensitive nanosensors based on poly(styrene-co-maleic anhydride) (PSMA). Dynamic light scattering identified polymer concentration as the primary determinant of particle size, with additional tunability provided by nonionic surfactants. Below the critical overlap concentration, increasing Reynolds number generally reduced particle size with lower dispersity. By varying these preparation conditions, monodisperse nanosensors with tunable hydrodynamic diameters of approximately 120-410 nm (polydispersity index, PDI < 0.1) were reproducibly obtained. In contrast, polymer concentrations above the critical overlap concentration produced polydisperse particles with mean hydrodynamic diameters exceeding 800 nm. Frame-straddling lifetime imaging showed an approximately linear Stern-Volmer response from anoxia to air saturation, with nonlinear behavior occurring only under supersaturated conditions. The nanosensors were successfully applied within the sensPIV framework, enabling simultaneous mapping of oxygen distributions and velocity fields around a living coral. Estimated hydrodynamic relaxation times indicated negligible inertial lag across the investigated particle-size range, whereas estimated oxygen equilibration times of approximately 0.04-4 ms suggested that finite sensor response may limit the resolution of the smallest scalar structures. These results establish flash nanoprecipitation as a reproducible and highly controllable route for preparing monodisperse polymeric nanosensors with tunable particle sizes for simultaneous scalar and velocity measurements.},
}

@article {pmid42781342,
year = {2026},
author = {Masclans, N and Jofre, L},
title = {Eigenspace-based reinforcement learning acceleration of statistical convergence in turbulent flows.},
journal = {Machine learning with applications},
volume = {25},
number = {},
pages = {None},
doi = {10.1016/j.mlwa.2026.100996},
pmid = {42781342},
issn = {2666-8270},
abstract = {Direct numerical simulation approaches play a critical role in advancing the understanding and accurate modeling of turbulent flow phenomena. However, the direct simulation of high-Reynolds-number turbulent flows is computationally intensive, requiring high spatial resolution and extended simulation times to achieve statistically reliable results. The strategy leverages deep reinforcement learning to apply dynamic, data-driven perturbations to the Reynolds stresses eigenspace. This allows an optimized control policy to guide the evolution of the Reynolds stresses tensor across all degrees of freedom (magnitude, anisotropy and orientation) within a physics-constrained framework. For the present numerical experiments, a reduced three-dimensional action space targeting magnitude and shape perturbations is utilized as an initial proof-of-concept. To that end, the framework is thoroughly described and its performance evaluated in the context of canonical turbulent channel flows at friction Reynolds numbers R e τ = 100 and R e τ = 180 . The trained agent successfully accelerates the convergence of key flow statistics, including the fluctuating velocity components and the underlying turbulent structure, i.e., anisotropy, particularly in the R e τ = 100 training case. A comprehensive computational cost analysis demonstrates that the training overhead is rapidly amortized during unsupervised evaluation phases.Depending on the training duration and early-stopping criteria, the initial training overhead is recovered within 3 to 10 deployment runs under the executed conservative time steps, and within 2 to 5 runs under the projected CFL-optimal conditions. This yields a net computational saving when accelerating the convergence of the fluctuating velocity components to their targeted error tolerances when extrapolating from the R e τ = 100 training case to the R e τ = 180 deployment case. Furthermore, the evaluation provided critical insights into the complex nature of the control problem, identifying main performance trade-offs during training, the strong dependency on the agent's actuation frequency, and the fundamental challenges of policy generalization to a new flow regime. This work validates, therefore, the presented approach as a viable tool for targeting the convergence acceleration of specific flow statistics, and demonstrates a clear path toward more computationally efficient high-fidelity simulations of turbulence.},
}

@article {pmid42782666,
year = {2026},
author = {Berce, J and Golobič, I},
title = {On the (In)Equality of Droplet Rebound Dynamics at Fixed Weber Number.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {11},
number = {9},
pages = {},
doi = {10.3390/biomimetics11090640},
pmid = {42782666},
issn = {2313-7673},
support = {P2-0223//The Slovenian Research and Innovation Agency/ ; J2-50085//The Slovenian Research and Innovation Agency/ ; },
abstract = {The similarity of droplet impacts on nature-mimicking superhydrophobic surfaces is traditionally compared using the dimensionless Weber number. Yet, maintaining a constant We by decoupling droplet diameter and impact velocity influences secondary forces, challenging this assumption of similarity. In this work, we investigate water droplet impacts on a lotus-leaf-mimicking laser-textured superhydrophobic aluminum surface at two constant Weber number levels (25 and 50), varying droplet diameter from 2.1 to 4.15 mm. Our results confirm that maximum spreading depends on the Reynolds number at a fixed We, as smaller, faster droplets spread less due to increased relative viscous dissipation. We propose a modified empirical scaling model that describes our data with high accuracy and generalizes successfully to external datasets. Crucially, we demonstrate that the contact time of a droplet of a given size is not strictly velocity-independent, unveiling a Weber number-dependent inertia-capillary scaling. We show that this is driven by a shift in rebound dynamics, where the relative timescale of spreading increases over retraction for larger droplets. These findings demonstrate that We is insufficient to characterize droplet rebound across varying scales and that accounting for size-dependent deviations is critical for the precise design of technologies that leverage droplet-surface interactions.},
}

@article {pmid42768652,
year = {2026},
author = {Liu, CC and Lin, JY},
title = {From Colebrook-White roughness to Nikuradse sand grains: A multiscale momentum-transfer model for turbulent friction over rough surfaces.},
journal = {Physical review. E},
volume = {114},
number = {2-2},
pages = {025109},
doi = {10.1103/xs83-z5nk},
pmid = {42768652},
issn = {2470-0053},
abstract = {Wall roughness plays a central role in determining turbulent friction in pipe flows, yet most predictive frameworks continue to characterize the wall by a single effective roughness scale. Classical datasets-notably Nikuradse's sand-grain experiments and the rough-pipe measurements of Colebrook and White-demonstrate that this description is incomplete: surfaces with comparable nominal roughness heights can exhibit markedly different friction curves, including branch splitting and multiregime behavior. Reexamining the Colebrook-White experiments, we identify clear evidence of multiscale additivity, whereby the contribution of a smaller roughness scale enters once it becomes dynamically accessible and increases approximately linearly with its areal coverage. Motivated by this observation, we develop a multiscale extension of the Gioia-Chakraborty momentum-transfer framework in which roughness elements at distinct geometric scales contribute additive increments to the total friction. In the model, each scale becomes dynamically active when its height exceeds a Reynolds-number-dependent viscous cutoff proportional to the Kolmogorov length, while its contribution is weighted by a scale-dependent coefficient representing the geometric prominence of that roughness scale. This construction generalizes the original scale-selection mechanism by allowing multiple roughness scales to participate concurrently in outer-layer momentum transfer. The resulting framework provides a unified and continuous description connecting the classical roughness-dominated Nikuradse-Strickler regime, Colebrook-White-type trends at intermediate roughness, and smooth-wall behavior. For the applications considered here, however, the model coefficients are not uniquely determined from surface properties and are selected in a data-guided manner; establishing a quantitative mapping from measured surface topography to these coefficients remains an open problem.},
}

@article {pmid42762291,
year = {2026},
author = {Yadav, S and Kumari, P and Yadav, V and Paulraj, S and Kumar, A and Mahto, SK},
title = {Chemotactic study of Escherichia coli towards alanine using a microfluidics platform.},
journal = {Bioprocess and biosystems engineering},
volume = {},
number = {},
pages = {},
pmid = {42762291},
issn = {1615-7605},
support = {DST/INT/BMWF/Austria/P-09/2020(G)//Department of Science and Technology, Ministry of Science and Technology, India/ ; },
abstract = {Chemotaxis, the capacity of cells and microorganisms to detect and respond to chemical gradients, is integral to various biological processes, including biofilm formation, environmental decontamination, pathogen identification, and targeted drug delivery. This study involved the fabrication of a Y-shaped microfluidic device to examine the chemotactic migration of Escherichia coli K12 DH5α toward gradient concentrations of alanine, an amino acid that serves as a potent chemoattractant for E. coli. The microfluidic device was designed and fabricated using standard photolithography and soft lithography techniques, and computational fluid dynamics (CFD) simulations were conducted using ANSYS Fluent to analyze the laminar flow behavior within the device. CFD simulations of phosphate-buffered saline (PBS) co-flow with 2 μm bacterial-sized particles predicted creeping, low-Reynolds-number laminar flow characterized by parallel, non-mixing streams, stable velocity profiles, and a smooth pressure drop of approximately 1.45 Pa toward the outlet. These results confirm the formation of a sharp interfacial boundary suitable for gradient-based chemotaxis assays. The chemotactic response of green fluorescent protein (GFP)-tagged E. coli was quantified by measuring fluorescence intensity in the central channel of the device. The results demonstrated that bacterial migration was dependent on alanine concentration, with maximum cell migration observed at 10 mM alanine. The bacteria exhibited motility perpendicular to the direction of streamlined laminar flow, migrating toward regions of higher alanine concentration. This study introduces a gradient-based Y-shaped microfluidic platform, validated through computational fluid dynamics (CFD), which integrates fluorescence-based quantification of GFP-tagged E. coli K12 DH5α chemotaxis. This platform facilitates real-time, reproducible, and concentration-dependent analysis of bacterial migration towards alanine under controlled laminar flow conditions. In contrast to traditional chemotaxis assays, it allows for precise chemical gradient generation, direct visualization of bacterial movement, and quantitative assessment of chemotactic responses within a single microfluidic system. The study provides both qualitative and quantitative insights into bacterial chemotaxis and highlights the potential of microfluidic platforms for real-time analysis of cellular behavior. The findings contribute to the advancement of rapid biosensing technologies and enhance the understanding of bacterial responses to chemical stimuli, with promising applications in biotechnology, microbiology, and environmental science.},
}

@article {pmid42744056,
year = {2026},
author = {Li, S and Alhazmi, M and Hilali, SO and Shah, Z and Jawaid, M and Shoaib, M},
title = {ANN-based analysis of heat transfer in blood-based hybrid nanofluid flow through a porous deforming channel.},
journal = {SLAS technology},
volume = {},
number = {},
pages = {100465},
doi = {10.1016/j.slast.2026.100465},
pmid = {42744056},
issn = {2472-6311},
abstract = {This paper is devoted to the investigation of thermal transport features of an Ag-TiO2 hybrid nanofluid based on blood, a non-deforming porous channel which is being heated up in different ways, and with the aim to find out its possible application in the field of biomedical thermal management systems. The study deals with the behavior of flow and heat of a blood-based hybrid nanofluid consisting of silver (Ag) and titanium dioxide (TiO2) nanoparticles in a rectangular channel with porous walls taking into account generalized thermal flux model effects. The problem is then regarded as a 2D incompressible laminar isothermal flow. The resulting PDEs are transformed into nonlinear ODEs via similarity transformations and solved numerically in the Mathematica software using NDSolve in order to create reference data. The influence of Reynolds number (R), wall deformation rate (α), and porosity parameter (S) on velocity and temperature profiles is investigated. A Bayesian regularized artificial neural network (ANN-BRT) is built to predict both velocity and temperature profiles with the use of numerically generated reference data, where 70% of the data is used for training and 15% for testing and validation. The model demonstrates excellent performance, with absolute errors shrinking from 10[-04] to 10[-09] and MSE values reaching the extremely low figure of 1.25 × 10[-12]. The metrics for performance validate the presence of very good convergence and reliability. It was found that the velocity is positively affected by higher values of porosity and Reynolds number, particularly in the case of wall deformation, while the temperature distribution behaves the opposite way as it is affected by wall injection and suction under higher Reynolds number and porosity conditions. This study opens up a variety of medical applications including drug delivery, cancer therapy, wound healing, and thermal management systems.},
}

@article {pmid42734708,
year = {2026},
author = {Patil, H and Untaroiu, A},
title = {The influence of stenosis severity and geometric orientation on atherosclerotic progression: A fluid-structure interaction study in the carotid artery.},
journal = {Physical and engineering sciences in medicine},
volume = {},
number = {},
pages = {},
pmid = {42734708},
issn = {2662-4737},
abstract = {Atherosclerosis remains the leading global cause of mortality, and its progression is strongly influenced by the local hemodynamic environment. Low Wall Shear Stress (WSS) is widely recognized as a promoter of atherosclerosis, yet the combined influence of stenosis severity and its geometric orientation on disease progression in anatomically realistic geometries has not been systematically examined. This study assesses the risk of atherosclerotic progression in a carotid artery using one-way Fluid-Structure Interaction (FSI). Four stenosis levels were simulated (0, 30, 60, and 80%), along with three angular orientations of the stenotic apex relative to the ICA wall. Blood flow was modeled using the [Formula: see text] SST turbulence model, and arterial walls were represented using a Mooney-Rivlin hyperelastic formulation. For 0% and 30% stenosed cases, regions of low Time-Averaged WSS (TAWSS <= 0.4 Pa) appeared in the ICA. In contrast, the 60% and 80% stenoses produced markedly elevated TAWSS at the stenosis throat, ranging from 20-60 Pa. Arterial wall deformation of the 0% and 30% cases was observed around 0.8 mm, while the 60% and 80% stenoses exhibited prominent foci of high deformation upto 2.1 mm. The presence of disturbed flow dynamics and their resulting atheroprogression risk was assessed through the interplay of Reynolds number, nondimensional WSS, nondimensional Turbulent Kinetic Energy (TKE) and the Oscillatory Shear Index (OSI). At 30% severity, the upstream-tilted stenosis intensified early-stage progression indicators, whereas at 60% severity, the downstream-tilted orientation increased plaque vulnerability. The study demonstrates a comparative framework to rank relative risk of atheroprogression using the disturbed flow signatures and wall mechanics observed across the 8 geometries.},
}

@article {pmid42731491,
year = {2026},
author = {Ye, D and Wu, B and Wang, Z and Xu, Z and Nikiforov, A and Ye, Z},
title = {Dual-gated interfacial oxidation enables dry purification of dye-wastewater recovery salt in a plasma fluidized bed.},
journal = {Water research},
volume = {308},
number = {Pt B},
pages = {126894},
doi = {10.1016/j.watres.2026.126894},
pmid = {42731491},
issn = {1879-2448},
abstract = {Dye waste salts extracted from dye-wastewater is a recoverable NaCl/Na2SO4-rich solid whose purification requires removal of interfacial organic residues while preserving the inorganic salt matrix. Here, we identify dual-gated interfacial oxidation as a site-pathway mechanism in a dielectric barrier discharge plasma fluidized bed. The first gate controls site formation: bubbling-like transport of 179 μm particles at 0.151 m·s[-1] repeatedly delivers organic-rich salt interfaces into discharge-accessible regions, while dynamic dielectric contacts redistribute current release from sparse bursts to more frequent microdischarge events, increasing the pulse counts from 8 ± 2 to 15 ± 5 per half-cycle while decreasing the inter-event-interval coefficient of variation (IEI-CV, dimensionless) from 0.45 to 0.25. The second gate controls pathway selection: oxygen-related excitation must be high enough to activate interfacial oxidation but not overdriven into ionization-weighted transport disruption. At 15.0 kV, the power-normalized O(I) emission index at 777.2 nm (ηO) reached 0.516 and coincided with the effective particle-transport/oxygen-excitation window defined by the coupled particle Reynolds number (ReP) and oxygen-related excitation index (ReP-ηO window); further voltage increases raised the N2[+]/N2 emission ratio but suppressed particle transport, separating stronger discharge from useful oxidation. Independent O2 perturbation further showed that the O(I)-based oxygen-related excitation response tracked the increase in TOC removal. Consequently, total organic carbon (TOC) removal peaked only when interfacial access and oxidation-relevant excitation converged, reaching 95.7%, with a TOC removal energy yield of 28.17 gTOC·kWh[-1]. Surface-organic depletion was accompanied by substantial carbon conversion, with CO2-C representing the largest quantified fate of removed carbon (57.1%), while FTIR and XPS confirmed depletion of organic-rich surface coverage while XRD and ion chromatography confirmed retention of the dominant NaCl/Na2SO4 matrix. Together these findings highlight a resource-oriented strategy for closing material loops in zero-liquid-discharge wastewater treatment systems.},
}

@article {pmid42722667,
year = {2026},
author = {Han, X and Chen, K and Wang, R and Wei, G and Han, L and Gao, H},
title = {Toward nonlinear representations with Gaussian-splat manifolds for physics-informed learning.},
journal = {Nature communications},
volume = {17},
number = {1},
pages = {},
pmid = {42722667},
issn = {2041-1723},
abstract = {Conventional linear discretizations, including high-order schemes, often require prohibitively many degrees of freedom to resolve sharp, localized features, and the practical advantages of nonlinear, physics-informed representations over fixed linear spaces remain unclear. Here we introduce a compact nonlinear-manifold representation, based on Gaussian splatting, for solving partial differential equations with discontinuities and thin shear layers. Mobile, anisotropic Gaussian kernels are evolved or optimized to satisfy the governing equations: time-dependent problems through a projection-based scheme on the manifold, and steady forward and inverse problems through direct residual minimization. The representation offers closed-form spatial derivatives and a highly compact description of sharp features. Across smooth, shock-dominated and shear-layer benchmarks, it attains accuracy comparable to classical solvers for smooth flows while remaining markedly more compact in strongly nonlinear regimes, and it displays an approximate error invariance as the Reynolds number increases-departing from the error accumulation inherent to linear representations.},
}

@article {pmid42717743,
year = {2026},
author = {Ravikumar, S},
title = {Electroosmotic-Peristaltic Propulsion of Ionic Jeffrey Fluid in Hall-Current-Modulated Magnetised Ciliated Porous Microchannel With Joule Heating and Soret-Dufour Cross-Diffusion.},
journal = {Electrophoresis},
volume = {},
number = {},
pages = {},
doi = {10.1002/elps.70152},
pmid = {42717743},
issn = {1522-2683},
abstract = {This study develops an analytical model for peristaltic-electroosmotic transport of an ionic Jeffrey fluid in a magnetised ciliated microchannel. Employing the Poisson-Boltzmann description with Debye-Hückel linearisation for electric potential distribution and adopting the long-wavelength, low Reynolds number approximations, the governing momentum, thermal energy and species concentration equations are reduced to analytically tractable forms. Closed-form expressions are obtained for velocity, temperature, concentration, pressure rise and wall shear stress. Parametric investigations reveal that elevated Hartmann number suppress fluid motion through enhanced Lorentz force resistance, whereas increasing Hall current and electroosmotic parameters accelerate ionic liquid transport by counteracting electromagnetic damping. The Darcy number exhibits a regime-dependent influence on pressure development across retrograde, augmented and free-pumping zones. Thermal analysis reveals that Joule heating and elevated Prandtl numbers amplify temperature fields, whereas thermal radiation and increased Biot numbers facilitate effective cooling by improving boundary heat dissipation. Ciliary geometric parameters, such as length and eccentricity, demonstrate non-linear interactions with electrokinetic forces, which significantly influence momentum, heat and mass transport characteristics. The results provide theoretical insight that may be useful for future studies of biomedical microfluidic transport and related design-oriented applications.},
}

@article {pmid42708230,
year = {2026},
author = {Hu, K and Yang, Y and Xu, J and Ouyang, Z},
title = {Motion characteristics of self-propelled particles in the wake flow past tandem circular cylinders.},
journal = {Soft matter},
volume = {},
number = {},
pages = {},
doi = {10.1039/d6sm00549g},
pmid = {42708230},
issn = {1744-6848},
abstract = {The Lattice Boltzmann method (LBM) is used to study the effects of the swimming Reynolds number Res, fluid Reynolds number Re, self-propulsion strength β, and cylinder spacing Δl on the obstacle-bypassing, wall-attached migration, and near-wall equilibrium behaviors of a squirmer in the Poiseuille flow inserted with a fixed tandem dual-cylinder obstacle array. The results show that the squirmer mainly exhibits four motion modes, i.e., downstream bypass, upper wall migration, downward bypass, and lower wall equilibrium. When the Res or |β| is small, the squirmer mainly undergoes downstream bypass, indicating that the background flow field and wake structure play dominant roles. As the self-propulsion is strengthened, the puller changes to downward bypass and further forms a lower wall equilibrium. For the pusher, gap-mediated obstacle escape occurs first, followed by upper wall migration under stronger self-propulsion conditions. Increasing Δl changes the wake structure in the gap region, thereby regulating the local obstacle-bypassing trajectory, wall contact turning point, and equilibrium position of the particle. Re further regulates the characteristic trajectory parameters and can induce transitions between swimming modes. This study provides a useful reference for the trajectory control of self-propelled particles in confined microchannels.},
}

@article {pmid42699718,
year = {2026},
author = {Sharma, PK and Lu, TY and Chen, CY},
title = {Modular reconfiguration and actuation of microrobotic assemblies.},
journal = {iScience},
volume = {29},
number = {9},
pages = {117208},
doi = {10.1016/j.isci.2026.117208},
pmid = {42699718},
issn = {2589-0042},
abstract = {Transport in microfluidic systems occurs under low-Reynolds-number conditions, where localized particle manipulation requires controlled fluid-structure interaction. Here, a modular magnetic microfluidic robotic assembly was developed using soft-bodied, hard-magnetic, and arc-shaped modules that self-assembled under external magnetic fields, underwent oscillatory actuation, and reversibly disassembled within the same platform. Field modulation enabled transitions between force- and torque-dominated regimes, allowing periodic deformation to be transmitted from the actuated legs to the functional head region. During oscillatory actuation, particles were redistributed via contact-assisted sweeping, accompanied by localized fluid disturbance. Forward and backward transport efficiencies of 91.1% ± 3.6% and 92.1% ± 2.6% were achieved, with a round-trip retention efficiency of 83.8% ± 4.8%. Frequency-dependent analysis identified an actuation condition that balanced deformation transmission and actuation rate. This work provides a basis for programmable microrobotic transport and localized manipulation in confined microfluidic environments.},
}

@article {pmid42685787,
year = {2026},
author = {Ijuptil, J and Houston, AJH and Kowal, KN and Mottram, NJ},
title = {Orienting-field effects on instability and mode selection in active nematics.},
journal = {Journal of physics. Condensed matter : an Institute of Physics journal},
volume = {},
number = {},
pages = {},
doi = {10.1088/1361-648X/aea1cf},
pmid = {42685787},
issn = {1361-648X},
abstract = {We examine the instabilities of a confined active nematic subjected to an orienting field using a low Reynolds number Ericksen-Leslie framework with active stresses and field-induced torques. Linear analysis reveals two distinct modes, with odd and even director symmetry, the instabilities of which depend on the interplay between activity and field strength. We derive exact and approximate analytic forms of the stability boundaries and show that an orienting field that aligns the director perpendicular to the substrate anchoring direction cooperatively lowers activity thresholds and enables a field-driven even symmetry mode instability, while an orienting field that aligns the director parallel to the substrate anchoring tends to stabilise the system. Numerical solutions of the full nonlinear equations show that the linear stability analysis correctly identifies the symmetries of long-time states. These results demonstrate how orienting fields can promote an instability below the classical critical activity and can be used to both tune the instability onset and control the mode selection in confined active nematics.},
}

@article {pmid42679686,
year = {2026},
author = {Rahmati, M and Chen, X},
title = {Enhancing deterministic lateral displacement performance using asymmetric gap geometries under high Reynolds number flow.},
journal = {Journal of chromatography. A},
volume = {1787},
number = {},
pages = {467373},
doi = {10.1016/j.chroma.2026.467373},
pmid = {42679686},
issn = {1873-3778},
abstract = {The separation and detection of suspended particles are critical in a wide range of applications, including cell sorting and medical diagnostics. Microfluidic deterministic lateral displacement (DLD) is a promising technique due to its ability to continuously separate particles based primarily on size with high resolution. However, achieving high-resolution particle separation remains challenging, as it requires reducing gap sizes, which significantly increases hydraulic resistance and reduces device throughput. In this study, DLD devices with asymmetric gap configurations are proposed to overcome this limitation. By independently varying vertical and horizontal gap sizes, the proposed design enhances separation resolution while mitigating the increase in hydraulic resistance. A comprehensive numerical model is developed to investigate the effects of gap asymmetry, row shift fraction, and Reynolds number on hydraulic resistance and critical diameter. The results show that increasing the vertical gap significantly reduces hydraulic resistance, whereas decreasing the horizontal gap improves separation performance, enabling more efficient particle displacement. Furthermore, the influence of moderate to high Reynolds number flows is examined, revealing that although inertial effects slightly increase hydraulic resistance, their overall impact is minor compared to the benefits of asymmetric gap design. Based on the simulation data, a regression-based predictive equation is derived to estimate the critical diameter as a function of key design and flow parameters. The proposed approach has the potential to improve throughput and separation resolution while offering advantages in fabrication, and may provide useful guidance for the design of high-resolution DLD devices.},
}

@article {pmid42665650,
year = {2026},
author = {Mengele, M and Zürn, J and Lochner, T and Weiß, U and Peter, MA and Bahnemann, J and Heuer, C},
title = {Comparative numerical and experimental evaluation of 3D-printed micromixers for biotechnological applications.},
journal = {Scientific reports},
volume = {16},
number = {1},
pages = {},
pmid = {42665650},
issn = {2045-2322},
mesh = {*Printing, Three-Dimensional ; Animals ; Cricetulus ; CHO Cells ; Hydrodynamics ; *Biotechnology/methods/instrumentation ; *Microfluidics/methods/instrumentation ; Equipment Design ; *Microfluidic Analytical Techniques/instrumentation ; Computer Simulation ; },
abstract = {Micromixers are essential in microfluidic-based biotechnology and diagnostics, where reproducible reactions and rapid mass transfer are crucial. Although many geometries exist, consistent comparison across dimensions, fabrication methods, and evaluation techniques remains challenging. In this study, we present a comparative analysis of six micromixer designs, focusing on mixing efficiency, pressure drop, shear stress, and the energy-dissipation rate. The devices were fabricated using high-definition 3D printing and studied experimentally and with high-resolution computational fluid dynamics (CFD) simulations. Tests covered a wide Reynolds-number range (Re = 0.1-200). At both ends of this range, most designs achieved adequate mixing. The greatest disparities emerged in the intermediate regime (Re = 1-50), with the Kenics geometry outperforming all other designs. Our grid-optimized CFD results matched experimental trends and quantified local shear and energy-dissipation rates. Live/dead assays using an industrially relevant Chinese hamster ovary (CHO) cell line showed unchanged viability immediately after mixing and during subsequent cultivation. By combining experimentally validated CFD predictions, systematic grid-optimized assessment, and biological validation within a single framework, this study establishes a consistent basis for comparing micromixer designs and selecting those that match desired combinations of mixing performance, pressure drop, volume, shear stress, and the energy-dissipation rate.},
}

*Printing, Three-Dimensional
Animals
Cricetulus
CHO Cells
Hydrodynamics
*Biotechnology/methods/instrumentation
*Microfluidics/methods/instrumentation
Equipment Design
*Microfluidic Analytical Techniques/instrumentation
Computer Simulation

@article {pmid42667365,
year = {2026},
author = {Aldaddi, A and Williams, E and Karakas, F and Maas, A and Murphy, D},
title = {Swimming Kinematics and Hydrodynamics of a Subtropical Sea Angel.},
journal = {Integrative and comparative biology},
volume = {},
number = {},
pages = {},
doi = {10.1093/icb/icag160},
pmid = {42667365},
issn = {1557-7023},
abstract = {Sea angels (gymnosomatous pteropods) are small zooplanktonic shell-less marine snails inhabiting the meso- and epipelagic zones. They swim in an intermediate Reynolds number regime using highly flexible, wing-like parapodia in order to capture prey, avoid predators, and perform diel vertical migration. However, the kinematics and fluid dynamics of gymnosome swimming are not well understood, particularly for species residing in low-viscosity, subtropical waters. Here we use high-speed stereophotogrammetry and dual brightfield particle image velocimetry (PIV) systems to investigate the swimming of the rare subtropical species Pneumoderma atlantica, captured off the coast of Bermuda. In particular, we quantify wing kinematics for hovering and slow upwards swimming and compare our results with morphologically similar temperate and polar species, which can be up to twice as large and swim in water up to twice as viscous. Like tiny insects flying in a similar regime, the chordwise Reynolds number appears to be inversely related to the wing angle of attack and stroke plane. Thus both the small, warm-water and the large polar gymnosomes seem to use their wings more like paddles to generate upward forces while the temperate species seems to use its parapodia more like wings to generate lift. Further, we provide the first flow measurements of a swimming gymnosome, these at somewhat higher swimming speeds, which show that gymnosomes employ an unsteady flow interaction between the wings and body (similar to the clap-and-fling mechanism) twice during each stroke cycle which likely generates additional lift. These findings provide insight into how similar locomotion modes may be adapted to different viscosities and into the widespread use of lift-generating, clap-and-fling-like mechanisms among marine snails.},
}

@article {pmid42661039,
year = {2026},
author = {Rathod, K and Joshi, K and Navalgund, L and Mubarak, NM and Chandra, S},
title = {Investigation of hydrodynamic and mass transfer characteristics in a draft tube spouted bed bioreactor (DTSBBR) for simultaneous COD and nitrate removal.},
journal = {Scientific reports},
volume = {16},
number = {1},
pages = {},
pmid = {42661039},
issn = {2045-2322},
mesh = {*Bioreactors ; *Nitrates/isolation & purification/metabolism ; Hydrodynamics ; Wastewater/chemistry ; Biofilms/growth & development ; *Biological Oxygen Demand Analysis ; Kinetics ; *Water Purification/methods ; Waste Disposal, Fluid/methods ; Denitrification ; },
abstract = {Because interactions among microbial growth kinetics, biofilm formation, hydrodynamic conditions, and mass transfer constraints frequently limit process stability and scale-up, the simultaneous removal of chemical oxygen demand (COD) and nitrate from wastewater remains a significant challenge in biological treatment systems. The hydrodynamic and mass transfer characteristics of a Draft Tube Spouted Bed Bioreactor (DTSBBR) were examined for the simultaneous removal of chemical oxygen demand (COD) and nitrate from synthetic wastewater under different operating parameters. In a biofilm-assisted reactor, performance was assessed at dilution rates (0.6, 0.9, and 1.2/h) and granular activated carbon (GAC) loads (10, 20, and 30 g). The biofilm thickness, substrate diffusion, external mass transfer coefficient, Reynolds number (Re), Schmidt number (Sc), and Sherwood number (Sh) were precisely studied and evaluated under the influence of reactor hydrodynamic studies. The COD elimination confirmed higher mass transfer capability compared to the nitrate values because of diffusion-limited denitrification kinetics, with Sherwood numbers ranging from 4.60 to 7.10 and mass transfer coefficients between 0.66*10[-6] and 1.04*10[-6] m/s. The empirical correlations Sh = 0.86 Re [0.52] Sc [0.33] for COD and Sh = 0.76 Re [0.50] Sc [0.33] for nitrate were obtained by diffusion-controlled substrate transport and substantial hydrodynamic dependence. The Monod kinetic experiments showed µmax values of 0.25/h for COD and 0.23/h for nitrate, with a constant Ks of 25 mg/L for COD and 14 mg/L for nitrate. The obtained results confirmed that DTSBBR provided consistent simultaneous organic and nitrogen removal, enhanced biofilm activity, and efficient substrate transport, demonstrating its applicability for advanced biological wastewater treatment applications.},
}

*Bioreactors
*Nitrates/isolation & purification/metabolism
Hydrodynamics
Wastewater/chemistry
Biofilms/growth & development
*Biological Oxygen Demand Analysis
Kinetics
*Water Purification/methods
Waste Disposal, Fluid/methods
Denitrification

@article {pmid42663769,
year = {2026},
author = {Pramanik, R},
title = {Emergent collective dynamics of microrobotic swarms in viscoelastic media: a computational perspective.},
journal = {The European physical journal. E, Soft matter},
volume = {49},
number = {9},
pages = {},
pmid = {42663769},
issn = {1292-895X},
mesh = {Viscosity ; *Elasticity ; *Robotics ; Rheology ; Computer Simulation ; },
abstract = {Microrobotic swarms are promising candidates for targeted drug delivery in complex physiological environments, including blood, mucus, and extracellular matrices. In such biomedical scenarios, collective motion is strongly influenced by low-Reynolds-number drag, crowding, confinement, viscoelasticity, and non-Newtonian rheology. This article envisages a mechanics-based computational framework for microrobotic swarms in viscoelastic (gel-like) media. Starting from Langevin dynamics, we derive the overdamped description appropriate for microscale agents and extend it to active Brownian particles with self-propulsion, local alignment, and short-range interparticle interactions. Cohesive and purely repulsive collective regimes are represented through Lennard-Jones and Weeks-Chandler-Andersen potentials, respectively. To model gel-like rheology, we introduce a fractional Kelvin-Voigt description of drag that incorporates power-law memory effects. The resulting stochastic dynamics are mapped to an explicit Euler-Maruyama algorithm with truncated-history fractional convolution, documented stabilizers, and diagnostic observables for polarization, clustering, trajectories, and transport. Beyond the model itself, the present study synthesizes recent work on bacterial living fluids, externally driven colloidal and microrobotic swarms, fish-school hydrodynamics, neural-network control of collective patterns, and cross-scale magnetic catheter-swarm thrombus removal. That microrobotic-swarm transport in biomedical media should not be treated only as a soft-matter problem is the primary takeaway. We believe that it is rather a coupled mechanics problem in which propulsion, interaction, memory, disorder, hydrodynamic communication, and clinical deliverability must be taken into consideration. At the same time, the preliminary simulations suggest a practically important biomedical trend: whereas Newtonian transport is more prone to collective aggregation, viscoelastic transport can preserve a more distributed swarm morphology, which is encouraging for controllable delivery, broader spatial coverage, and aggregation-resistant payload transport in complex bodily fluids.},
}

Viscosity
*Elasticity
*Robotics
Rheology
Computer Simulation

@article {pmid42645290,
year = {2026},
author = {Gao, M and Wei, Z and Wu, Z and Zhang, C and Shen, C},
title = {Turbulent Drag Reduction Research on Biomimetic Surfaces Based on the Microstructural Characteristics of Shark Skin.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {11},
number = {8},
pages = {},
doi = {10.3390/biomimetics11080573},
pmid = {42645290},
issn = {2313-7673},
support = {ZR2024QE320//Shandong Provincial Natural Science Foundation/ ; ZR2023QE209//Shandong Provincial Natural Science Foundation/ ; XY23BS41//Heze University Doctoral Research Foundation/ ; 52305306//National Natural Science Foundation of China/ ; 52275289//National Natural Science Foundation of China/ ; },
abstract = {In engineering fields such as aviation, shipping, and high-speed rail, system operational efficiency and energy consumption are largely determined by turbulent drag. The drag reduction design of shark skin-inspired micro-groove structures have opened up new avenues for improving aerodynamic efficiency, optimizing flow field characteristics, and saving energy, representing a highly promising research hotspot in the field of functional micro-structured surfaces. Addressing the issue of drag reduction for V-shaped grooves (frictional Reynolds number 85-695), this paper employs Design of Experiments (DOE) combined with high-precision numerical simulation to clarify the influence of groove height (h), groove width (s), and inflow velocity (U) on the drag reduction rate for bionic microgroove surfaces. The drag reduction mechanism is further revealed through the analysis of vorticity distribution, vortex core position, boundary layer velocity distributions, pulsating velocity fields, and Reynolds stress distributions. When the dimensionless height h[+] and width s[+] range from 8.50 to 29.75, these grooves can effectively reduce resistance. A maximum drag reduction rate of 12.33% is achieved at h[+] = s[+] = 25.29 and a flow velocity of 80.7 m/s (frictional Reynolds number 599). At low flow velocities, larger groove dimensions are favorable for drag reduction. In contrast, smaller groove dimensions are required under medium-to-high flow velocity conditions. The optimal microstructural dimensions of V-shaped grooves decrease as the inflow velocity increases. V-shaped grooves can lift turbulent vortex coherent structures, reduce pulsating velocities in the streamwise, normal, and spanwise directions, and decrease the peak values of Reynolds stress in the near-wall region. The results can provide a quantitative basis for the design and engineering applications of biomimetic riblet drag-reducing surfaces.},
}

@article {pmid42648533,
year = {2026},
author = {Park, Y and Kim, B and Seo, IW and Baek, S and Cho, SK},
title = {Weathering alters the settling dynamics of polyethylene microplastics: Integrating morphology-dependent drag coefficient with numerical simulations.},
journal = {Environmental pollution (Barking, Essex : 1987)},
volume = {},
number = {},
pages = {128995},
doi = {10.1016/j.envpol.2026.128995},
pmid = {42648533},
issn = {1873-6424},
abstract = {Weathering alters the physical properties of microplastics and can modify their transport behavior in aquatic systems, but its impact on settlement dynamics remains under-quantified. This study investigates how physico-chemical weathering affects the morphology and settling behavior of polyethylene microplastics by integrating laboratory experiments with numerical simulations. Particles underwent four laboratory-simulated weathering scenarios combining mechanical stirring, ultraviolet irradiation, and hydrogen peroxide treatment. Weathering resulted in substantial mass loss (∼25%) and systematic geometric changes, indicating size reduction accompanied by partial shape regularization. A numerical model based on an ad hoc Maxey-Riley formulation with a morphology-dependent drag coefficient was validated against independent experimental data (R[2] = 0.90). Modeling results show that weathering reduced the terminal settling velocity by 5.2-7.1% relative to pristine particles. Mechanical stirring produced the largest reduction (6.7%) through particle size reduction and the associated mass loss, whereas hydrogen peroxide partially offset this reduction (+1.6%) through shape regularization. Ultraviolet irradiation had a negligible effect (<0.5%). These secondary effects were associated with slight shape regularization, partially compensating for the velocity reduction. When particle shape was explicitly incorporated into the corrected Reynolds number, settling velocities collapsed into a single scaling relationship (R[2] > 0.99). These findings demonstrate that weathering causes slower settling of particles through size reduction, while shape-induced drag acts as a secondary but important factor in improving predictions of microplastic transport.},
}

@article {pmid42629832,
year = {2026},
author = {Khan, MM and Thampi, SP and Roy, A},
title = {Radiation forces and torques on Janus cylinders.},
journal = {Physical review. E},
volume = {114},
number = {1-2},
pages = {015409},
doi = {10.1103/cwhj-21kh},
pmid = {42629832},
issn = {2470-0053},
abstract = {We investigate radiation-induced drag, lift, and torque on circular Janus cylinders under transverse-magnetic plane-wave illumination, considering metallodielectric and purely dielectric configurations. The lattice Boltzmann method (LBM) is employed with absorption neglected, isolating scattering as the sole momentum-transfer mechanism. For metallodielectric Janus cylinders, analytical expressions for radiation force and torque are derived and used to validate the LBM, showing excellent agreement across a wide range of dielectric constants and interface orientations. For dielectric Janus cylinders, material inhomogeneity induces asymmetric scattering giving rise to nonzero lift and torque under plane-wave illumination, with nonmonotonic dependence on interface orientation and dielectric contrast. Two mechanisms govern the observed variations: resonance-driven energy amplification and scattered field redistribution. The computed force and torque maps serve as design diagrams for predicting the optomechanical response. Coupling these with viscous dynamics at low Reynolds number reveals diverse particle trajectories, including curved paths during reorientation and nearly straight motion once torque-free equilibria are reached. The system is externally actuated and results represent scattering-dominated dynamics under idealized conditions, providing physical insight into optomechanical responses of Janus particles with implications for trajectory shaping in optofluidic systems.},
}

@article {pmid42629893,
year = {2026},
author = {Verma, S and Seshasayanan, K and Raynaud, R and Guilet, J},
title = {Large Pm small-scale kinematic dynamo in protoneutron stars.},
journal = {Physical review. E},
volume = {114},
number = {1-2},
pages = {015221},
doi = {10.1103/qxm8-gl1p},
pmid = {42629893},
issn = {2470-0053},
abstract = {Magnetars are young, isolated neutron stars that possess an exceptionally strong magnetic field, with surface dipolar strengths on the order of 10^{15}G
. One of the plausible scenarios for generating such a strong field is an exponential amplification by a turbulent convective dynamo during the protoneutron star phase. However, the short expected duration of the convection (∼10s) imposes a stringent constraint on the dynamo growth rate. We perform an extensive set of 82 three-dimensional convective dynamo simulations in the anelastic approximation and investigate the kinematic phase to quantify the dynamo growth rate γ. We find that γ increases with both the magnetic Prandtl number Pm and the Rayleigh number Ra, with the most unstable mode becoming highly nonaxisymmetric and multipolar. We further observe a gradual transition from large-scale to small-scale dynamo as the magnetic Reynolds number Rm increases, resulting in a magnetic field that is predominantly concentrated at small scales. The trend remains unchanged when the outer magnetic boundary condition is varied. Since resolving the increasingly small scales becomes numerically impractical, we employ the theoretical small-scale Kazantsev dynamo model to explore the large Pm regime characteristic of protoneutron stars. The model qualitatively captures the growth rate behavior observed in simulations and, upon extrapolation to the large Pm limit, indicates that γ is only weakly dependent on the resistivity in a PNS. Under conditions relevant to the PNS, this model predicts a magnetic energy growth rate of the order of ∼1ms^{-1}.
},
}

@article {pmid42630053,
year = {2026},
author = {Atzori, M and Gallorini, E and Cottini, C and Benassi, A and Quadrio, M},
title = {Direct Numerical Simulations of Inhalation in a 23-Generation Lung Model.},
journal = {International journal for numerical methods in biomedical engineering},
volume = {42},
number = {8},
pages = {e70208},
doi = {10.1002/cnm.70208},
pmid = {42630053},
issn = {2040-7947},
support = {//Italian Research Center on High Performance Computing Big Data and Quantum Computing (ICSC), European Union - NextGenerationEU - and National Recovery and Resilience Plan (NRRP) - Mission 4 Component 2./ ; },
mesh = {Humans ; *Lung/physiology ; *Models, Biological ; *Computer Simulation ; *Inhalation/physiology ; },
abstract = {The air flows in the proximal and distal portions of the human lungs are interconnected: the lower Reynolds number in the deeper generations causes a progressive flow regularization, but mass conservation requires flow rate oscillations to propagate through the airway bifurcations. To explain how these competing effects shape the flow state in the deeper generations, we have performed the first high-fidelity numerical simulation of the air flow in a lung model that includes 23 successive bifurcations of a single planar airway. Turbulence modeling or assumptions on flow regimes are not required. The chosen flow rate is steady on average, and representative of the peak inspiratory flow reached by adult patients breathing through therapeutic inhalers. As expected, advection becomes progressively less important after each bifurcation, until a time-dependent Stokes regime governed solely by viscous diffusion is established in the smallest generations. However, fluctuations in this regime are relatively fast and large with respect to the mean flow, which is in contrast with the commonly agreed picture that only the breathing frequency is relevant at the scale of the alveoli. We demonstrate that the characteristic frequency and amplitude of these fluctuations are linked to the flow in the upper part of the bronchial tree, as they originate from the time-dependent flow splitting in the upper bifurcations. Even though these fluctuations are observed here in an idealized, rigid lung model, our findings suggest that the assumptions usually adopted in many of the current lung models might need to be revised.},
}

Humans
*Lung/physiology
*Models, Biological
*Computer Simulation
*Inhalation/physiology

@article {pmid42618782,
year = {2026},
author = {Lagemann, C and Mokbel, S and Gondrum, M and Rüttgers, M and Wang, Y and Suárez, P and Paehler, L and Bezgin, DA and Buhendwa, AB and Callaham, JL and Ahnert, S and Zolman, N and Shao, X and Loiseau, JC and Adams, NA and Meinke, M and Schröder, W and Lagemann, K and Lagemann, E and Vinuesa, R and Brunton, SL},
title = {The HydroGym reinforcement learning platform for fluid dynamics.},
journal = {Nature},
volume = {},
number = {},
pages = {},
pmid = {42618782},
issn = {1476-4687},
abstract = {Effective control of fluid flows is critical across transportation, energy and medicine, where it can increase lift, reduce drag, enhance mixing and attenuate noise[1-3]. Yet fluids are notoriously difficult to control because they involve high-dimensional, nonlinear and multiscale dynamics that resist conventional approaches[4-6]. Reinforcement learning has driven remarkable progress in fields such as protein folding and complex games, which have shared benchmarks and standardized environments[7-10]. Fluid dynamics has lacked such infrastructure, so each controller is typically tuned to a single geometry and operating condition, making progress difficult to accumulate, transfer and compare[11-13]. Here we introduce HydroGym, a solver-independent reinforcement learning platform providing more than 60 validated, openly available flow control environments spanning from canonical laminar flows to complex turbulent flows, with systematic progression in the Reynolds number up to Re = 4 × 10[5], and Mach number variations in two and three dimensions. Across these environments, agents repeatedly discover robust control principles, including boundary layer manipulation, disruption of acoustic feedback and reorganization of turbulent wakes. Critically, we demonstrate a proof of concept for zero-shot transfer, in which agents that are trained exclusively in inexpensive surrogate environments are deployed to challenging real-world scenarios such as a three-dimensional wing section. We achieve a 38% reduction in local skin friction while reducing exploration costs by four orders of magnitude compared with direct on-wing optimization. As this transfer exploits shared near-wall physics, the breadth of generalization remains open, suggesting a new pathway for research toward policy generalization across computationally prohibitive simulation environments. By offering a common, extensible foundation for reproducible research, HydroGym moves flow control from isolated case studies toward a cohesive community effort.},
}

@article {pmid42597854,
year = {2026},
author = {Albalawi, AM and Hassan, ZO and Roberts, WL and Elbaz, AM},
title = {Structure of Turbulent Nonpremixed Syngas Jet Flames in a Heated Coflow at Elevated Pressure.},
journal = {ACS omega},
volume = {11},
number = {31},
pages = {45789-45803},
pmid = {42597854},
issn = {2470-1343},
abstract = {This study investigates the effects of coflow preheat temperature and elevated pressure on the structure of turbulent nonpremixed syngas jet flames representing conditions relevant to the integrated gasification combined cycle (IGCC) combustion systems. Experiments were conducted using the KAUST high temperature and pressure duct (HTPCD). The study begins by establishing a stability curve for different nitrogen dilution ratios versus blowoff jet velocity, revealing a nonlinear relationship between nitrogen content in the jet and blowoff velocity; the blowoff velocity decreases from approximately 76 m/s for undiluted syngas to approximately 32 m/s at 45% nitrogen dilution. Selected flame conditions, with varying jet velocities (25-45 m/s) and nitrogen content (15-30%), are analyzed under four different pressure and coflow temperature conditions: 1 bar at 295 K, 1 bar at 373 K, 5 bar at 295 K, and 5 bar at 373 K. Direct flame imaging and OH-PLIF techniques are used to examine the appearance, structure, OH corrugation, and thickness of the flame. The results demonstrate that flames with higher jet velocities are more significantly affected by elevated coflow temperatures, resulting in shorter luminous flame lengths and increased corrugation. In contrast, for lower jet velocities (25 m/s), luminous flame length and corrugation are largely unaffected by preheat temperature, owing to a competing reduction in Reynolds number caused by the lower gas density at elevated temperatures. Increasing the pressure to 5 bar enhances the corrugation of the flame in all conditions and reduces the visible length of the flame, regardless of the conditions of the jet. Furthermore, increasing either jet velocity or nitrogen dilution ratio decreases the thickness of the OH layer, although this effect diminishes in high-pressure flames. Coflow preheating consistently increases OH layer thickness (from approximately 1.4 mm to 1.8 mm at atmospheric pressure), while elevated pressure reduces it (from approximately 1.8 mm at 1 bar to approximately 1.2 mm at 5 bar). Higher coflow temperatures also increase the thickness of the OH layer regardless of pressure. One-dimensional (1-D) counterflow diffusion flame simulations provide chemical-kinetic support for the observed experimental trends, particularly the widening of the OH distribution at higher air preheat temperatures.},
}

@article {pmid42581059,
year = {2026},
author = {Kumar, GM and Kumar, KM and Mothilal, T},
title = {Parametric sweep assessment of cross-slit cylinders for passive drag reduction and wake modification.},
journal = {Scientific reports},
volume = {16},
number = {1},
pages = {},
pmid = {42581059},
issn = {2045-2322},
abstract = {This paper presents a detailed numerical investigation and parametric sweep assessment of cross-slit (CS) cylindrical configurations aimed at passive drag reduction and wake modification in low to transitional Reynolds number regimes relevant to marine and offshore applications. A series of two-dimensional laminar CFD simulations were performed at Reynolds numbers of 100, 150, and 300 to analyze the influence of slit width ratio (SWR = 0.10-0.25) and sweep angle on wake dynamics, drag, lift, and vortex shedding characteristics. . A systematic mesh-independence study with Grid Convergence Index estimates and time-step sensitivity analysis were conducted to ensure numerical reliability. The results reveal that intermediate sweep configurations (SWR = 0.15-0.20) effectively modify alternating vortex shedding and reduce wake by promoting early shear-layer reattachment. Compared to conventional and single-slit cylinders, the optimized CS designs achieved 26-32.5% drag reduction, up to 40-52.5% reduction in reattachment length,, and a 93.1% reduction in Strouhal number at Re = 100,, indicating weekened vortex shedding intensity, and modified wake topology Increasing Reynolds number enhanced flow instability, yet the optimized CS geometry retained improved hydrodynamic stability and reduced fluctuating lift amplitudes. Wake vorticity analysis confirmed that cross-slit perforations alter the coherent vortex street by delaying shear-layer roll-up and extending the near-wake region. The observed trends in drag reduction, wake stabilisation, and shedding frequency modification indicate that cross-slit cylinders serve as a promising passive hydrodynamic control mechanism with potential implications for offshore risers, underwater structural supports, and marine energy devices.},
}

@article {pmid42585113,
year = {2026},
author = {Huang, S and Saurabh, A and Pressé, S},
title = {Correlated fluctuating hydrodynamics. II. Scale-dependent Reynolds numbers.},
journal = {The Journal of chemical physics},
volume = {165},
number = {6},
pages = {},
doi = {10.1063/5.0329396},
pmid = {42585113},
issn = {1089-7690},
abstract = {Many chemical and biological processes in molecular, soft-matter, and living systems are modeled using the low-Reynolds-number (Re ≪ 1) linearization of the incompressible Navier-Stokes equations. This approximation is justified by the assumption that viscous dissipation dominates nonlinear inertial effects across spatial scales. However, many soft-matter and biological fluids possess internal structure that modifies momentum transport across scales, potentially altering the balance between inertial and viscous effects. In Part I [J. Chem. Phys. 165, 064509 (2026)] of this series, we introduced a thermodynamically consistent fluctuating-hydrodynamic framework for structured fluids and showed that spatial correlations render viscous dissipation scale dependent. Here, we investigate the consequences of this scale dependence for the validity of the classical low-Re linearization. We show that scale-dependent viscous dissipation alters the balance between inertia and viscosity across scales, thereby invalidating the conventional low-Re justification for linearization. Direct numerical simulations in one and two dimensions confirm these predictions. In one dimension, nonlinear mode coupling accelerates the relaxation of high-wavenumber Fourier modes relative to the linearized dynamics. The same mechanism is reflected in particle transport in two dimensions: the particle velocity autocorrelation decays more slowly under the linearized dynamics, leading to diffusion coefficients that differ from the nonlinear prediction by up to 90%. These results demonstrate that a single Reynolds number is no longer sufficient to determine the validity of linearization in spatially correlated fluctuating fluids; instead, it depends on a scale-dependent spectrum of effective Reynolds numbers.},
}

@article {pmid42586626,
year = {2026},
author = {Li, H and Yu, X and Lu, S},
title = {A framework for predicting the flow behaviour of liquid foams enhanced by xanthan gum and sodium carboxymethyl cellulose across different systems.},
journal = {Carbohydrate polymers},
volume = {389},
number = {},
pages = {125582},
doi = {10.1016/j.carbpol.2026.125582},
pmid = {42586626},
issn = {1879-1344},
abstract = {Predicting the flow of foam across different geometries is a critical challenge, particularly when the continuous phase is a polymer-based non-Newtonian fluid. To address this challenge, foams were prepared using two distinct non-Newtonian fluids. In rotational rheometry, the power-law and Bingham models adequately described the constitutive behaviour of non-Newtonian fluid-based foams. Afterwards, quantitative relationships between the structure of the foam (bubble size and expansion ratio), the constitutive behaviour of the solutions, and the constitutive behaviour of the foam (yield stress, consistency coefficient, and flow index) were established. In pipe, the friction factor-Reynolds number relationship for non-Newtonian fluid-based foams exhibits nonclassical scaling with an exponent of 0.84, significantly deviating from 1 for Newtonian fluid-based foams. After incorporating a wall slip correction, the coefficient increases from 16.8 to 22.9. These findings indicate that the friction factor-Reynolds number correlation varies significantly with the properties of the base fluid. Moreover, models for apparent viscosity and stress-shear rate that integrate the bubble diameter and polydispersity index successfully bridge the gap between benchtop rheometry and industrial-scale pipeline flow. This study provides a framework that moves beyond configuration-specific correlations, and offers predictive power for the design of processes in several areas, including food processing and enhanced oil recovery.},
}

@article {pmid42572302,
year = {2026},
author = {Nakai, Y and Araki, O and Nakamura, T and Seki, M and Tanaka, Y and Ikeda, A and Fujii, S},
title = {Recurrent Migration of Fish Bone Foreign Bodies into the Intrahepatic Bile Duct After Pancreaticoduodenectomy Identified by DNA Metabarcoding: A Case Report with Pathophysiological Considerations.},
journal = {Internal medicine (Tokyo, Japan)},
volume = {},
number = {},
pages = {},
doi = {10.2169/internalmedicine.7543-26},
pmid = {42572302},
issn = {1349-7235},
abstract = {Fish bone migration into the bile duct after pancreaticoduodenectomy (PD) is rare, and the mechanism of recurrent migration is unclear. We report a case in which multiple fish bones were repeatedly identified and removed from the intrahepatic bile duct during four endoscopic retrograde cholangiopancreatography procedures over more than six years after PD. The foreign bodies were definitively identified as fish bones using a component analysis and DNA metabarcoding. These findings suggest that recurrent migration may occur even in the absence of apparent anatomical abnormalities and it may be associated with postoperative intestinal dysmotility and altered intraluminal flow dynamics.},
}

@article {pmid42573334,
year = {2026},
author = {Ahmad, M and Mininni, PD and Obligado, M and Farnsworth, JA},
title = {Dynamical Hysteresis in the Dissipation in Turbulent Flows.},
journal = {Physical review letters},
volume = {137},
number = {4},
pages = {044001},
doi = {10.1103/mt2v-yqtb},
pmid = {42573334},
issn = {1079-7114},
abstract = {We present evidence of the dynamical hysteretic nature of dissipation in unsteady turbulent flows. Wind tunnel experiments and direct numerical simulations in oscillating flows show that, at stationary mean Reynolds number, the dissipation constant is larger for decelerating flows. Consequently, a periodic behavior of the flow produces a hysteresis cycle, whose area scales with a parameter combining the Strouhal number and the relative amplitude of the forcing. This phenomenon can be explained and quantified through the influence of the unsteady term in the Kármán-Howarth equation, with implications for a wide range of out-of-equilibrium systems.},
}

@article {pmid42561018,
year = {2026},
author = {Xiao, X and Zeng, X and Zhou, J and Pang, T and Zhou, T and Song, J and Li, L and Xu, B and Li, Y and Wu, G and Guo, Y},
title = {Multifunctional miniature robots: Harnessing the photothermal effect of magnetic microparticles for light and magnetic control.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {123},
number = {32},
pages = {e2610882123},
doi = {10.1073/pnas.2610882123},
pmid = {42561018},
issn = {1091-6490},
support = {52375560//MOST | National Natural Science Foundation of China (NSFC)/ ; },
abstract = {Developing miniature robots with multimodal mobility in complex environments remains challenging. This study developed miniature robots based on magnetic particle-doped liquid crystal elastomers (LCEs) that integrate multicomponent functional doped materials and LCE molecular orientation engineering. Thanks to the synergistic introduction of magnetic particles with photothermal effects and 5CB plasticizer, the robot exhibits fast photothermal response in both terrestrial and underwater environments. In the terrestrial environment, the designed photomagnetic dual-field coupling strategy reshapes the physical boundaries of robots, improving their obstacle-crossing ability and achieving asymmetric full-orientation dual-mode jumping. In the underwater environment, the robot utilizes frequency laser flapping to induce wake vortex rings to overcome moderate Reynolds number drag. Especially, by utilizing the spatial resolution of the local light field, it successfully achieves efficient directional propulsion and flexible steering control by switching the irradiation position to break fluid symmetry, substantially alleviating the spatial-control limitations of globally applied magnetic fields. Finally, we demonstrated potential applications of designed miniature robots on targeted photothermal therapy of cancer cells with high accuracy. We expect that the newly developed dual-responsive and multifunctional miniature robots will find broad medical applications, such as targeted drug delivery and minimally invasive surgery.},
}

@article {pmid42545559,
year = {2026},
author = {González-García, JS},
title = {Microswimming as a mechanism for mitochondrial wiggling.},
journal = {Journal of biological physics},
volume = {52},
number = {1},
pages = {},
pmid = {42545559},
issn = {1573-0689},
mesh = {*Mitochondria/metabolism ; *Models, Biological ; Movement ; Hydrodynamics ; Chloroplasts/metabolism ; },
abstract = {In many plant cells, there are two types of mitochondrial motion: directed and wiggling. While the former is mediated by F-actin and microtubules, the latter is not. The fact that mitochondria migrate via wiggling suggests the existence of other mechanisms of motion aside from those related to the cytoskeleton and protein motors. In this work, it is assumed that wiggling mitochondria are active Brownian particles, self-propelled bodies whose motion at low Reynolds number is affected by noise. The proposed mechanism of motion is microswimming, where a wiggling mitochondrion is driven by a cycle of shape changes resembling a peristaltic wave travelling along its body. The peristaltic wave is modelled on a two-sphere swimmer under the far-field approximation, yielding expressions for the kinetic and dynamic variables involved, as well as for the factors determining its interaction with chloroplasts. The calculations show that the microswimmer can reach reported speeds with small size deformations and explain the observed high percentage of wiggling mitochondria captured by chloroplasts. Using the hydrodynamic results enables the application of a theoretical probabilistic model, including active and passive noise, which fits well with experimental results on speed distribution and trajectories of wiggling mitochondria. Taken together, the results explain the main mitochondrial wiggling characteristics observed in experiments, thus suggesting the feasibility of microswimming as a mechanism for mitochondrial wiggling.},
}

*Mitochondria/metabolism
*Models, Biological
Movement
Hydrodynamics
Chloroplasts/metabolism

@article {pmid42528846,
year = {2026},
author = {Ho, HH and Essel, EE and Sullivan, PE},
title = {Actuation parameters and boundary layer height effects on a circular synthetic jet in crossflow.},
journal = {Discover fluid mechanics},
volume = {2},
number = {1},
pages = {7},
pmid = {42528846},
issn = {3059-3158},
abstract = {UNLABELLED: Three-dimensional unsteady numerical simulations are performed to investigate the effects of blowing ratio [Formula: see text] ([Formula: see text]), stroke ratio [Formula: see text] ([Formula: see text]), and boundary-layer height ratio [Formula: see text] (2.1<δ /d<8.0) on circular synthetic jet actuator (SJA) performance in crossflow. Nine cases are examined at constant free-stream velocity [Formula: see text], with systematic independent variation of averaged jet velocity [Formula: see text], actuation frequency f (200-[Formula: see text]), and boundary-layer momentum thickness Reynolds number ([Formula: see text]) to examine the influence of these parameters across varying boundary-layer conditions on a circular-nozzle SJA with fixed nozzle diameter d in crossflow. Instantaneous vortical structures exhibited tilted vortex rings with a trailing vortex pair at low actuation frequency; closely packed expelled vortical structures for higher frequency SJAs, and the largest boundary-layer height ratio induced hairpin-like vortices. Near-wall tertiary vortices, which promote downwash and increase wall shear stress, remain coherent longer and have extended spanwise coverage for low [Formula: see text]. Time-averaged boundary-layer profiles and skin-friction distributions reveal that SJAs with low to moderate [Formula: see text] have the greatest potential for separation control, maintaining increased near-wall momentum over extended streamwise distances.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s44369-026-00011-9.},
}

@article {pmid42531303,
year = {2026},
author = {Yao, H and Zaki, T and Meneveau, C},
title = {Lagrangian finite-time fluctuation relation in isotropic turbulence.},
journal = {Philosophical transactions. Series A, Mathematical, physical, and engineering sciences},
volume = {384},
number = {2325},
pages = {},
doi = {10.1098/rsta.2025.0030},
pmid = {42531303},
issn = {1471-2962},
support = {CSSI-2103874//NSF/ ; },
abstract = {The entropy generation rate in turbulence can be defined using the energy cascade rate as described in the scale-integrated Kolmogorov-Hill equation at a specified length scale. The fluctuation relation (FR) from non-equilibrium thermodynamics, which predicts exponential behaviour of the ratio of probability densities for positive and negative entropy production rates, was confirmed in a prior work by Yao et al. (Yao et al. 2023 J. Fluid Mech. 973, R6. (doi:10.1017/jfm.2023.808)), but under certain limiting assumptions. We here examine the applicability of FR to isotropic turbulence under less stringent assumptions by analysing entropy generation rates averaged over intervals ranging from one to several eddy turnover times. Based on time-resolved data at a Taylor-scale based Reynolds number Reλ=433, we find that the FR is valid in the sense that very close to exponential behaviour of probability ratios of positive and negative entropy generation (forward and inverse cascade of energy) is observed. Interestingly, finite-time averaging yields FR-consistent results only within a Lagrangian framework, along fluid trajectories using filtered convective velocities. By contrast, the FR does not hold with time-averaging at fixed (Eulerian) positions. Results provide evidence that the definition of entropy generation based on the scale-integrated Kolmogorov-Hill equation describes turbulent cascade processes that exhibit properties predicted by non-equilibrium thermodynamics. This article is part of the theme issue 'Frontiers of turbulence and statistical physics'.},
}

@article {pmid42531314,
year = {2026},
author = {van Kan, A and Alexakis, A and Knobloch, E},
title = {Two-dimensional turbulent condensates without bottom drag.},
journal = {Philosophical transactions. Series A, Mathematical, physical, and engineering sciences},
volume = {384},
number = {2325},
pages = {},
doi = {10.1098/rsta.2025.0019},
pmid = {42531314},
issn = {1471-2962},
support = {A0190506421//HPC resources of GENCI-TGCC & GENCI-CINES/ ; PHY230056//NSF ACCESS/ ; ANR-17-CE30-0004//Agence nationale de la recherche/ ; DMS-2009563//National Science Foundation/ ; DMS-2308337//National Science Foundation/ ; 522026592//German Research Foundation/ ; 82023//France-Berkeley Fund/ ; },
abstract = {The extent to which equilibrium statistical theory is applicable to driven dissipative dynamics remains an important open question in many systems. We use extensive direct numerical simulations (DNS) of the incompressible two-dimensional (2D) Navier-Stokes equation to examine the steady state of large-scale condensates in 2D turbulence at finite Reynolds number Re in the absence of bottom drag. Large-scale condensates appear above a critical Reynolds number Rec≈4.19. Close to this onset, we find a power-law scaling of the energy with Re-Rec, with the energy spectrum at large scales following the absolute equilibrium form proposed by Kraichnan. At larger Re, the energy spectrum deviates from this form, displaying a steep power-law range at low wavenumbers with exponent -5, with most of the energy dissipation occurring within the condensate at large scales. We show that this spectral exponent is consistent with the logarithmic radial vorticity profile of the condensate vortices predicted by quasi-linear theory for a viscously saturated condensate. Our findings shed new light on the classical problem of large-scale turbulent condensation in forced dissipative 2D flows in finite domains, showing that the large scales are close to equilibrium dynamics in weakly turbulent flows but not in the strong condensate regime with Re≫1. This article is part of the theme issue 'Frontiers of turbulence and statistical physics'.},
}

@article {pmid42531316,
year = {2026},
author = {Migdal, A},
title = {Geometric solution of turbulent mixing.},
journal = {Philosophical transactions. Series A, Mathematical, physical, and engineering sciences},
volume = {384},
number = {2325},
pages = {},
doi = {10.1098/rsta.2025.0345},
pmid = {42531316},
issn = {1471-2962},
support = {SFI-MPS-T-MPS-00010544//Simons Foundation/ ; },
abstract = {We derive an analytic solution for the density of a passive scalar in decaying homogeneous turbulence, in the limit of high Reynolds number and fixed Schmidt number. The velocity statistics are described by the Euler ensemble, previously obtained as a spontaneously stochastic solution of the loop equation associated with the Navier-Stokes equations. The scalar advection-diffusion problem is formulated as a closed linear loop equation and solved within this framework. For a localized initial condition, the solution consists of a sequence of expanding concentric shells. The radial scalar profile is piecewise parabolic and supported at discrete radii, with amplitudes determined by Euler totients. This structure differs from conventional scaling descriptions of scalar turbulence. Finite diffusivity or sustained forcing smooths the discontinuities while preserving the leading-order geometry. The results provide a geometric description of scalar transport in decaying turbulence and may be relevant in regimes where dissipation is weak, such as astrophysical or quantum fluids. The predicted shell structure is difficult to resolve directly in numerical simulations; however, its statistical signature is captured by the volume-averaged scalar density, which provides a practical observable. This article is part of the theme issue 'Frontiers of turbulence and statistical physics'.},
}

@article {pmid42513004,
year = {2026},
author = {Yang, J and Buren, M},
title = {Alternating Current Electroosmotic Flow of Viscoelastic Jeffreys Fluids in a pH-Regulated Slit Nanochannel.},
journal = {Micromachines},
volume = {17},
number = {7},
pages = {},
doi = {10.3390/mi17070793},
pmid = {42513004},
issn = {2072-666X},
support = {2024LHMS01008//the Natural Science Foundation of Inner Mongolia/ ; },
abstract = {This study investigates the electroosmotic flow (EOF) of viscoelastic Jeffreys fluids in a pH-regulated parallel-plate nanochannel, with a focus on analyzing the effects of solution pH, background salt concentration, and alternating current (AC) electric field frequency on flow characteristics. In micro- and nanoscale fluidic systems, surface charge characteristics critically govern electrokinetic flow. The surface charges in this study originate from the protonation and deprotonation reactions of silanol (SiOH) groups on the channel walls. Different from the constant surface electric potential assumed in existing studies, the surface electric potential here varies with solution pH and background salt concentration. By modulating solution pH and thereby tuning surface charge density, active and reversible control of EOF can be realized. By solving the coupled Poisson-Boltzmann equation, momentum equation, and Jeffreys constitutive equation, we obtain an analytical solution for the electric potential distribution and semi-analytical solution for the velocity field. The results show that under the chosen parameter conditions, the relaxation time λ1 enhances the velocity amplitude, while the retardation time λ2 weakens it. The EOF velocity amplitude of Jeffreys fluids is enhanced by greater pH deviation from the isoelectric point, lower ionic concentration, and higher electric field frequency. In nanochannel flows, the effect of the oscillating Reynolds number on the velocity amplitude is negligible.},
}

@article {pmid42517634,
year = {2026},
author = {Tomita, Y and Hwang, JH and Kang, G},
title = {Cavitation bubble dynamics following lithotripter-induced shock wave-gas bubble interaction in viscous compressible blood.},
journal = {The Journal of the Acoustical Society of America},
volume = {160},
number = {1},
pages = {839-856},
doi = {10.1121/10.0044256},
pmid = {42517634},
issn = {1520-8524},
abstract = {The equation of motion for a cavitation bubble following lithotripter-induced shock wave and gas bubble nucleus interaction in a viscous compressible blood is derived using the Keller-Miksis model, together by applying a Casson equation as a constitutive equation for blood flow, and numerical calculations have been performed for the initial bubble radii R0, 1-10 μm. Following the shock wave-gas bubble interaction, a cavitation bubble is formed when the shock wave pressure tail enters the negative pressure region, and it expands to reach the maximum radius Rmax. The Rmax value decreases linearly as R0 decreases for whole blood, plasma, and water. Among the three types of liquids, whole blood tends to exhibit the smallest Rmax value due to the influence of apparent viscosity. During cavitation bubble collapse, a high Reynolds number flow is developed in the whole blood, in which the apparent viscosity approaches Casson viscosity. Eventually, the bubble collapse dominated by inertial effect can produce impulsively high pressures on the order of several hundreds to thousands of gigapascals with the pulse width of 7.5 ps to 0.11 ns (i.e., full width at half maximum). A pair of impulsive collapse pressure pulses, with the collapse pressure ratio of 27-789, occur with the occurrence frequency of approximately 9 kHz for whole blood.},
}

@article {pmid42503133,
year = {2026},
author = {Liu, XR and Chen, X and Peng, SH and Zhang, YB and Xi, HD},
title = {Experimental Observation of the Area Rule and Bifractality of Circulation in Three Dimensional Newtonian and Polymeric Turbulence.},
journal = {Physical review letters},
volume = {137},
number = {2},
pages = {024001},
doi = {10.1103/fj29-8l44},
pmid = {42503133},
issn = {1079-7114},
abstract = {Velocity circulation around closed loops is a fundamental quantity of central interest in the study of the energy cascade in turbulent flows. Recent theoretical and numerical studies have identified circulation as a geometric observable that captures intermittency through the area rule and a distinctive bifractal scaling of its moments in classical and quantum turbulence. One fundamental question is how these statistical characteristics of circulation are altered when an additional agent such as long-chain flexible polymer that can modify the turbulence energy cascade is added to the fluid. Here, through stereo particle image velocimetry measurements in high Reynolds number (R_{λ}�
��393) turbulent flow of pure water and dilute polymer solution in a von Kármán swirling flow system, we provide the first experimental evidence that the area rule and the bifractality of the circulation hold for planar loops in both the 3D Newtonian and polymeric turbulence. These two statistical characteristics of circulation are robust despite strong modifications of the energy cascade and small-scale topology induced by polymer elasticity, except that the Hölder exponent in polymeric turbulence (h≈1.55) is significantly larger than in Newtonian turbulence (h≈1.14), suggesting that the flow is smoother in polymeric turbulence. Our results establish velocity circulation as a more universal and fundamental tool, compared to the very frequently used velocity increments, for unifying intermittency across different turbulent systems from Newtonian to polymeric to quantum turbulence.},
}

@article {pmid42480187,
year = {2026},
author = {Mahaveer, and Zima, P},
title = {Progress and key influencing factors in vortex separator technologies: A comprehensive review on optimization and similarity principles.},
journal = {Water research},
volume = {305},
number = {},
pages = {126531},
doi = {10.1016/j.watres.2026.126531},
pmid = {42480187},
issn = {1879-2448},
abstract = {Vortex separators have become indispensable small units for the treatment of multiphase streams and particle-laden flows in wastewater, stormwater management and environmental protection industries. Despite the vast application, there is not yet a unified understanding of the joint control of separation performance and similarity scaling by structural configuration, operational parameters, and characteristics of particles. This review synthesizes new developments based on inlet-outlet configurations, internal baffling and vortex-forming elements, along with key hydraulic variables including surface loading rate, hydraulic retention time and inflow velocity over wide ranges of particle sizes, densities and concentrations. The analysis uncovers mechanistic relationships of the flow structure, turbulence and particle trajectories. Principal dimensionless parameters particularly Peclet number (Pe), Reynolds number (Re), and Froude number (Fr) are identified for enabling performance transfer from laboratory models to full-scale systems. The research establishes that meaningful optimization involves simultaneous consideration of the structural, hydraulic and particle domains. Future directions in theoretical development and structural innovation are provided to guide vortex separator design for the next generation.},
}

@article {pmid42475363,
year = {2026},
author = {Punyaratabandhu, N and Pankoh, T and Roongthumskul, Y and Dechadilok, P and Katavetin, P},
title = {Pathways for glomerular macromolecule filtration: A mathematical model for transport across glomerular filtration surface, mesangium and shear-induced shunts.},
journal = {PLoS computational biology},
volume = {22},
number = {7},
pages = {e1014503},
doi = {10.1371/journal.pcbi.1014503},
pmid = {42475363},
issn = {1553-7358},
abstract = {A mathematical model is developed to investigate the relative contribution of macromolecule transport across the glomerular filtration surface and that across mesangial area to glomerular size-selectivity. Endothelial fenestrae are assumed to be filled with glycosaminoglycans. Glomerular basement membrane (GBM) is a hydrogel containing two types of fibers. Slit diaphragm is a row of parallel cylinders with inter-fiber spacing following a lognormal distribution. Glomerular mesangium is viewed as a Brinkman medium with solute diffusivity and convection rate calculated from hydrodynamic forces exerted on confined spheres. Comparison between calculated sieving coefficients and those of Ficolls from in vivo studies demonstrates that inclusion of fluxes across the filtration surface and mesangial area, although capable of explaining small and medium-sized solute sieving, underestimates filtration of macromolecules with radii larger than 5 nm. Based on electron micrographs displaying red blood cells escaping through openings at the junction between the filtration surface and mesangium, the location with maximum shear stress, the present study examines effects of these openings using low-Reynolds-number hydrodynamics. Even though such effects on filtration of small and moderate-sized solutes are negligible, the presence of possibly shear-induced openings amplifies sieving of large macromolecules, yielding calculated sieving coefficients that agree well with those obtained from urinalysis in healthy humans and patients with diabetic nephropathy for the entire range of solute radii. While the glomerular filtration surface is the main pathway for small and moderate-sized solutes, main passages of large macromolecules are likely to be through the shear-induced openings, explaining the "upper limit" of glomerular size-selectivity.},
}

@article {pmid42477021,
year = {2026},
author = {Shbailat, SJ and Ridha, HD},
title = {Constructal theory of aerodynamic design in NACA airfoils for search and rescue UAVs using integrated CFD and ANN approaches.},
journal = {Scientific reports},
volume = {16},
number = {1},
pages = {},
pmid = {42477021},
issn = {2045-2322},
abstract = {Constructal design of the NACA (National Advisory Committee for Aeronautics) airfoil was to reduce the drag force and increase the lift force for search and rescue (SAR) missions. This series of NACA airfoils is defined by a 4-digit NACA mptt, which indicates the camber, the location of maximum camber, and the thickness. Three degrees of freedom can be used to optimize aircraft airfoils using constructal theory. The CFD (Computational Fluid Dynamics) 2-D simulation was conducted in ANSYS FLUENT version (15), and the SST k-ω model turbulence equations were used to solve the incompressible Reynolds-averaged Navier-Stokes (RANS) equations. Simulations are performed using MATLAB's Neural Network ANN (Artificial Neural Network), which enables a robust surrogate-based algorithm for the design study. The highest Cl/Cd ratio indicates the trade-off between lift and drag. An airfoil with a high Cl/Cd (lift-to-drag coefficient) ratio produces more lift than drag, thereby enhancing aerodynamic performance through comparative analysis of three degrees of freedom (m, p, t) at low Reynolds numbers ([Formula: see text] and [Formula: see text]). NACA 4412 makes a better Cl/Cd ratio, 1.38 at 4[Formula: see text]-12[Formula: see text], than NACA 4418, about 26% higher at the same AoA 4[Formula: see text]-12[Formula: see text]. An increase in Reynolds number led to higher Cl/Cd ratios, 1.38 at angles of attack (AoAs) of [Formula: see text], compared to NACA 4418, about 26% higher at the same AoAs of [Formula: see text]. across all profiles, indicating higher aerodynamic efficiency. It is particularly applicable to search-and-rescue UAVs, which can operate at varying speeds and altitudes depending on mission requirements. The ANN model has determined the optimal AoA and Reynolds number that maximizes the Cl/Cd ratio of the NACA 4412 airfoil. The CFD results are validated against ANN results, which are based on experimental results used to train the artificial intelligence algorithm to predict ANN results from the present study.},
}

@article {pmid42477391,
year = {2026},
author = {Hassaan, AM},
title = {Thermo-hydraulic and second-law analysis of a shell-and-tube heat exchanger using water, propylene glycol, and glycerol mixtures in the laminar-transition regime.},
journal = {Scientific reports},
volume = {16},
number = {1},
pages = {},
pmid = {42477391},
issn = {2045-2322},
abstract = {This study presents a comprehensive experimental investigation of the thermo-hydraulic and second-law performance of a shell-and-tube heat exchanger operating under counter-flow conditions. Water, propylene glycol/water (PG/water), and glycerol/water mixtures at different concentrations were employed as working fluids to evaluate the influence of thermophysical properties on heat-transfer, hydraulic, and exergy characteristics. A total of 105 experimental runs were conducted over a Reynolds number range of 400-4800, covering laminar and transitional flow regimes. The overall heat transfer coefficient, pressure drop, Nusselt number, friction factor, entropy generation, and exergy efficiency were systematically analyzed and compared under identical operating conditions. The results demonstrated that increasing Reynolds number significantly enhances heat-transfer performance, resulting in higher overall heat-transfer coefficients and Nusselt numbers. However, this improvement is accompanied by increased pressure losses and entropy generation, reflecting the thermodynamic trade-off between heat-transfer enhancement and irreversibility. Among the investigated fluids, water exhibited the highest thermal and exergy performance, whereas glycerol/water mixtures produced the lowest performance due to their higher viscosity and associated flow resistance. To provide practical predictive tools, empirical correlations were developed for both the Nusselt number and friction factor based on the complete experimental dataset. The proposed correlations were expressed as Nu = 2.43*Re^0.30*Pr^0.094 and f = 5.47 Re^-0.62*Pr^-0.08, showing satisfactory agreement with the experimental measurements. Validation against established literature correlations confirmed the capability of the proposed models to predict thermal and hydraulic performance within the investigated Reynolds number range. The novelty of the present work lies in the comparative experimental assessment of water, propylene glycol/water, and glycerol/water mixtures under identical operating conditions, together with the simultaneous evaluation of thermal, hydraulic, and second-law performance metrics and the development of predictive correlations based on an extensive experimental database. The findings provide reliable benchmark data and engineering correlations that can support the design, optimization, and exergy-based evaluation of heat exchangers operating with viscous heat-transfer fluids in industrial thermal systems.},
}

@article {pmid42467179,
year = {2026},
author = {Gupta, R and Shah, P and Mohite, A and Pandey, NP and Soni, R and Tevar, N and Sharma, A and Solanki, H},
title = {Experimental investigation and ANN modeling of thermo-hydraulic characteristics of GO nanofluid in a tube equipped with wire-coil inserts.},
journal = {Discover nano},
volume = {21},
number = {1},
pages = {},
pmid = {42467179},
issn = {2731-9229},
abstract = {Heat transfer enhancement techniques play a crucial role in improving the thermal efficiency of heat exchangers while minimizing energy usage and operational expenses. In this study, the thermo-hydraulic performance of a circular tube equipped with wire-coil inserts and operating with graphene oxide (GO) nanofluid was predicted using an artificial neural network (ANN) model. Experiments were conducted over a Reynolds number range of 5000-18,000 using GO nanofluid with weight concentrations of 0.025-0.1 wt% and wire-coil inserts having pitch-to-diameter ratios (P/D) of 1, 1.5, and 2. The experimental findings revealed that the combined use of GO nanofluid and wire-coil inserts significantly enhanced the Nusselt number, although it also resulted in an increase in the friction factor. At a GO concentration of 0.05 weight% and a P/D ratio of 1.5, the maximum Thermal Performance Factor of 1.21 was attained, signifying an ideal thermo-hydraulic balance. A feed-forward backpropagation ANN model was created with the Reynolds number, nanoparticle concentration, and P/D ratio as input parameters and the Nusselt number and friction factor as outputs in order to forecast system performance. The correctness and dependability of the suggested model were confirmed by the ANN predictions having outstanding agreement with the experimental findings.},
}

@article {pmid42469345,
year = {2026},
author = {Muftuoglu, TD},
title = {Physics-constrained machine-learning surrogates for the colebrook friction factor: monotonic gradient boosting, uncertainty quantification, and open benchmarking.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-62231-w},
pmid = {42469345},
issn = {2045-2322},
abstract = {The Darcy-Weisbach friction factor is used to determine the head losses occurring due to friction in pressurised pipes. It is defined by the Colebrook-White Equation as an implicit function of the Reynolds number and relative roughness for which iterative methods are generally required. Explicitly derived approximations can be obtained very quickly but have parameter dependent errors, do not guarantee monotonicity, and give no indication of the level of uncertainty associated with these approximations. Most existing Machine Learning Surrogate models produce accurate representations but rarely constrain their predictions to enforce physically meaningful monotonic relationships, nor provide probabilistic estimates of their reliability. This paper develops a Monotonic Gradient Boosting (MGB) surrogate model that constrains its predictions based on physics-based monotonic relationships and provides both calibrated error bound approximations using quantile boosting and split conformal prediction methods as well as a transparent benchmarking protocol. On the fixed [Formula: see text] evaluation grid, rough-pipe subset ([Formula: see text], 144 cases), the surrogate achieved MAPE = 0.168% and maximum absolute error = [Formula: see text]; on the stratified held-out test set it achieved MAPE = 0.25%. The empirical coverage for nominal 95% prediction intervals was 95.5%. There were no violations to monotonicity across all 1,829 Reynolds number and 1800 relative roughness changes. The explicit baseline models achieved an average absolute percentage error (MAPE) of 0.236% (Haaland), 0.546% (Swamee-Jain), and 0.012% (Serghides). While Serghides is still superior in terms of point accuracy than the others, the MGB provides both monotonicity constraints and calibration bounds on approximation errors to provide a reliability certificate that cannot be found using any closed form expressions.},
}

@article {pmid42455662,
year = {2026},
author = {Zhang, S and Ma, Q and Xie, W and Liu, K and Su, Y and Zhao, M and Wang, Z and Zhao, J and Liu, X},
title = {Super-Darcy flow behavior in fracture-confined porous media.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {123},
number = {29},
pages = {e2613597123},
doi = {10.1073/pnas.2613597123},
pmid = {42455662},
issn = {1091-6490},
support = {2023YFB4005500//MOST | National Key Research and Development Program of China (NKPs)/ ; },
abstract = {Particle deposition and migration within fractures can reorganize open void space into heterogeneous fracture-confined porous media (FCPM), yet the macroscopic flow behavior of these emergent systems remains unresolved. Here, Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) simulations were used to resolve particle migration and deposition, whereas a coupled free-flow and seepage-flow model was employed to characterize fluid flow in FCPM. We find that at a fixed Reynolds number, modest particle deposition can lower the overall pressure drop relative to that of the initially open fracture. At high Reynolds numbers, the pressure drops across FCPM not only exceed Darcy's law predictions (non-Darcy behavior) but, intriguingly, can also fall below them, which is a phenomenon we term super-Darcy behavior. This counterintuitive effect arises from flow exchange between the deposited porous region and the adjacent open region, which modifies eddy formation and growth, thereby broadening the main flow channel. This effect is pronounced when the permeability of the deposited porous region lies from 1 × 10[-12] to 1 × 10[-7] m[2], identifying a permeability window in which deposition-migration most strongly couples pore-scale structure to fracture-scale hydraulics. This study reveals how particle deposition and transport govern macroscopic flow behavior in fractured channels, offering critical insights for fluid flow control and prediction from microfluidic devices to subsurface energy reservoirs.},
}

@article {pmid42444570,
year = {2026},
author = {Ballentine, WM and Chan, KYK and Wong, E and Wong, JY and Koehl, MAR},
title = {Hydrodynamic effects of spines on zooplankton: How horns and tails alter flow and forces on barnacle nauplii.},
journal = {The Journal of experimental biology},
volume = {},
number = {},
pages = {},
doi = {10.1242/jeb.252318},
pmid = {42444570},
issn = {1477-9145},
support = {2451609//Division of Integrative Organismal Systems/ ; 2136019//Division of Integrative Organismal Systems/ ; },
abstract = {Many planktonic animals have body extensions (spines) that might affect the hydrodynamic performance of ecologically-important functions. Because crustacean naupliar larvae have a wide range of spine morphologies, they provide useful model systems to study spine hydrodynamics. Here we focus on nauplii with long anterior (horns) and posterior (tail) spines: the feeding nauplii of common flotsam-dwelling barnacles, Lepas anserifera, with long pelagic larval duration. We investigated hydrodynamic consequences of anterior and posterior spines using dynamically-similar physical models of these nauplii with horns and tails that could be removed. Models were towed through a viscous fluid at speeds to match the Reynolds numbers of locomoting and feeding L. anserifera nauplii. Hydrodynamic forces and torques on the models were measured, and particle image velocimetry (PIV) was used to quantify flow velocity fields around them. We found that both horns and tail spines increase drag, which resists swimming. However, they improve stability by counteracting the moments generated by beating appendages. Additionally, spines prolong the residence time of food-carrying water parcels near the particle-capture region of a nauplius, likely improving feeding performance. These findings highlight the trade-offs between the performance of different ecological functions, e.g. swimming versus feeding, that can exert selective pressures on morphology.},
}

@article {pmid42446621,
year = {2026},
author = {Riasat, S and Iqbal, S and Hina, S and Mir, A and Hassen, W and Kolsi, L and Ghachem, K},
title = {Modeling of electro-diffusive ternary nanofluid flow between rotating disks using the Poisson-Nernst-Planck framework with a non-Fourier heat-flux model.},
journal = {Discover nano},
volume = {21},
number = {1},
pages = {},
pmid = {42446621},
issn = {2731-9229},
support = {NBU-FFR-2026-2928-01//Deanship of Scientific Research at Northern Border University, Arar, KSA/ ; PNURSP2026R41//Princess Nourah bint Abdulrahman University Researchers/ ; },
abstract = {This work analyze the unsteady axisymmetric electro-diffusive flow and heat transfer of a ternary nanofluid between two rotating disks within the Poisson-Nernst-Planck (PNP) framework, using a Tiwari-Das-type effective single-phase mixture description for the ternary nanofluid. The model incorporates electro-viscous effects, a magnetic field, porous-medium resistance, temperature-dependent thermal conductivity, homogeneous and surface-catalyzed heterogeneous reactions, and the non-Fourier heat-flux law. The numerical results were obtained utilizing MATLAB's bvp4c solver. The outcomes show that enhancing the Schmidt number reduces concentration profiles, while increasing the chemical reaction and surface-catalyzed reaction parameters reduces concentration. The temperature field increases with variable thermal conductivity and is more strongly enhanced by blade-shaped nanoparticles than by spherical particles, whereas stronger thermal radiation and larger thermal relaxation reduce the temperature distribution. In addition, increasing the Reynolds number decreases the tangential velocity. These findings provide an integrated numerical assessment of how established electro-viscous, reactive, variable-conductivity, and non-Fourier heat-transfer mechanisms interact in a ternary-nanofluid rotating-disk system.},
}

@article {pmid42449114,
year = {2026},
author = {Chang, K and Li, Y and Yuan, M and Sano, M and You, Z and Zhang, HP},
title = {Bacterial turbulence drives interfacial waves and shape dynamics in phase-separated droplets.},
journal = {Nature communications},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41467-026-75497-5},
pmid = {42449114},
issn = {2041-1723},
support = {12225410, 12074243, 12374219//National Natural Science Foundation of China (National Science Foundation of China)/ ; 2021YFA0910700, 2023YFA1407500//Ministry of Science and Technology of the People's Republic of China (Chinese Ministry of Science and Technology)/ ; },
abstract = {Liquid-liquid phase separation is important across biology, physics, and materials science. Although usually studied at equilibrium, active components-such as motor proteins, enzymes, and synthetic microswimmers-are increasingly recognized as key players in reshaping phase separation dynamics. Yet how internally generated active stresses are transmitted to capillary interfaces to reshape three-dimensional droplet dynamics remains poorly understood. Here, we encapsulate dense suspensions of motile bacteria inside phase-separated aqueous droplets, creating a closed droplet whose interface is driven from within by bacterial turbulence. By varying bacterial density, we control the active stress at the droplet interface. At low bacterial density, we observe scale-dependent interfacial fluctuations that propagate as waves. In this low Reynolds number regime, these waves arise from an effective inertial response, generated when active bacterial stresses balance passive viscous damping of the interface. At higher bacterial density, droplets deform strongly-exceeding the Plateau-Rayleigh instability threshold-and even form bacteria-scale filaments-a morphology without a passive counterpart. Enhanced droplet motility and accelerated coarsening accompany these shape changes. Our work shows how active stresses can reshape the morphology and dynamics of multiphase systems, offering new insight into the physics of internally driven phase-separated fluids.},
}

@article {pmid42437765,
year = {2026},
author = {Asai, T and Liu, R and Kimachi, K and Hong, S},
title = {Comparative study of the aerodynamic characteristics and flight behavior of the FIFA World Cup 2026 ball Trionda.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-56275-1},
pmid = {42437765},
issn = {2045-2322},
abstract = {This study systematically compares the aerodynamic characteristics of four FIFA World Cup official footballs, including the 2026 ball Trionda, using wind tunnel measurements and simplified trajectory analysis. Drag coefficients and time-resolved side and lift forces were measured over flow speeds of 7-35 m/s (Re ≈ 1.1 × 10[5]-5.2 × 10[5]). Unsteady aerodynamic behaviour was quantified using both root-mean-square (RMS) values and power spectral density (PSD) analysis. In addition, the influence of panel orientation was assessed through an additional configuration for Trionda. All balls exhibited a drag crisis, with Trionda showing the lowest critical Reynolds number (≈ 1.78 × 10[5]), followed by Al Rihla, Brazuca, and Telstar. In the supercritical regime, Trionda exhibited a consistently higher drag coefficient (≈ 0.22). PSD results revealed broader spectral energy and enhanced fluctuations for Trionda compared with Al Rihla, indicating increased wake unsteadiness. Orientation effects introduced measurable but limited variation without altering the overall aerodynamic trends. Simplified trajectory simulations indicate shorter flight distances for Trionda at high speeds, reflecting its higher drag. These results provide a physically consistent baseline for comparing ball aerodynamics under controlled conditions and offer insight into potential variations in ball flight behaviour under match-relevant conditions.},
}

@article {pmid42436240,
year = {2026},
author = {Al-Khazragie, ZK and Thamir, KH and Sabri, M and Sabri, L and Abbood, HA and Sohrabi, M and Hamedinia, M},
title = {Removing hydrogen sulfide and carbon dioxide from natural gas using iron oxide nanoparticles and a magnetic field.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-60889-w},
pmid = {42436240},
issn = {2045-2322},
abstract = {This paper is one of the few studies that examine the use of water-amine nanofluid along with iron oxide nanoparticles with volume fraction ϕ = 0 to 0.05 to remove acid gases ([Formula: see text] and CO2) from natural gas. In this research, real-size refinery equipment was simulated using Fluent software, and the effects of nanoparticles and a constant magnetic field on increasing the heat transfer rate and the removal rate of acid gases from natural gas were investigated. The results show that in the absorption tower, with the increase of the Reynolds number from Re = 8000 to 24,000, the Nusselt number also increases, and with the rise of the ϕ to 0.05, the mole fraction of [Formula: see text] in the nanofluid increases to 34%, and the mole fraction of CO2 increases to 23%. Additionally, as the temperature increases, the dynamic viscosity of the nanofluid decreases. However, when the volume fraction (ϕ) increases to 0.05, the dynamic viscosity of the nanofluid approximately increases by 10% in the temperature range of 45 to 56 [Formula: see text]. In this research, magnetic field intensities ranging from 0 to 20,000 Gauss were used. With ϕ=0.01, the mentioned magnetic fields increase the mass transfer coefficient to 13.26%. With ϕ = 0.05, the mass transfer coefficient decreases to 4.44% due to the increased probability of nanoparticles settling. The maximum mass transfer coefficient is up to 67.4%, which is observed in ϕ = 0.03, with the magnetic field intensity of 20,000 gauss. A limitation of this research was the failure to evaluate the effect of changing the fluid flow regime on other refinery equipment.},
}

@article {pmid42428941,
year = {2026},
author = {Helan Princey, C and David Maxim Gururaj, A},
title = {Mathematical modeling and analysis of magnetic nanoparticle- induced heating in cerebrospinal fluid flow using a core-shell Fe3O4@Au nanoparticles for targeted drug therapy.},
journal = {Frontiers in bioengineering and biotechnology},
volume = {14},
number = {},
pages = {1827203},
pmid = {42428941},
issn = {2296-4185},
abstract = {BACKGROUND: Neurological disorders often require effective delivery of therapeutic agents to specific regions of the central nervous system. Magnetic nanoparticles have emerged as a promising approach for improving targeted drug delivery through cerebrospinal fluid (CSF) under externally applied magnetic fields. However, the combined effects of porous media, magnetic forces, nanoparticle transport, and magnetic heating on CSF flow remain insufficiently understood.

METHODS: In this study, a mathematical model is developed to investigate the flow and heat transfer characteristics of CSF containing Fe3O4@Au magnetic nanoparticles in a porous channel. The Brinkman--Darcy framework is employed to describe the flow, while magnetic body forces are incorporated through the Kelvin force model. Heat generation arising from the magnetic response of nanoparticles is included in the energy equation. The governing equations are transformed into dimensionless form and solved analytically using a perturbation technique to obtain expressions for velocity, temperature, volumetric flow rate, wall shear stress, and Nusselt number.

RESULTS: The analysis reveals that increasing permeability, Reynolds number, and magnetic interaction parameter enhances the velocity and volumetric flow rate of the nanofluid. In contrast, increasing nanoparticle volume fraction reduces fluid velocity due to the associated increase in effective viscosity. Temperature is found to increase significantly with magnetic heating, while higher thermal conductivity promotes heat diffusion and reduces thermal accumulation. The wall shear stress follows trends similar to velocity, increasing with permeability, Reynolds number, and magnetic forces. The Nusselt number is strongly influenced by magnetic heating and thermal conductivity, highlighting the competing effects of heat generation and heat diffusion.

DISCUSSION AND CONCLUSION: The results demonstrate the significant role of magnetic forces, porous medium properties, and nanoparticle characteristics in controlling CSF transport and thermal behavior. The proposed model provides insight into the transport and distribution of magnetic nanoparticles in CSF and may contribute to the design and optimization of magnetically guided drug delivery systems for neurological applications.},
}

@article {pmid42429364,
year = {2026},
author = {Livitz, D and Dhatt-Gauthier, K and Bishop, KJM},
title = {Magneto-Capillary Dynamics of Janus Ellipsoids for Droplet Propulsion.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.6c00962},
pmid = {42429364},
issn = {1520-5827},
abstract = {Magnetic microrobots propelled by time-varying fields can transport solid cargo through viscous fluids; however, the field-driven transport of liquid droplets remains less explored. Here, we investigate whether a magnetic particle adsorbed at a droplet interface can act as a "tugboat," propelling a much larger droplet using spatially uniform magnetic fields. In the strong capillary limit, the drop-particle pair behaves as a rigid composite object whose motion is governed by symmetry constraints characteristic of low Reynolds number flows. Within this framework, we show theoretically that a ferromagnetic ellipsoid adsorbed on a spherical droplet can generate steady propulsion in a precessing field when its magnetic moment is oblique to the particle axes. We develop a dynamical model that predicts droplet propulsion and identifies combinations of particle aspect ratio, precession angle, and driving frequency that maximize the propulsion speed. We perform experiments on magnetic Janus ellipsoids adsorbed on water drops in decane to quantify their magneto-capillary motion, validate key features of the model, and infer the magnitude and orientation of the magnetic moment. Although the symmetry of the ellipsoids studied here precludes an experimental demonstration of drop propulsion, our combined theoretical and experimental results establish key design principles for engineering magnetic microrobots capable of towing and manipulating liquid droplets.},
}

@article {pmid42430608,
year = {2026},
author = {Datt, C and Bauermann, J and Budanur, NB and Jülicher, F},
title = {Fluid Flow and Spatiotemporal Chaos in Chemically Active Emulsions.},
journal = {Physical review letters},
volume = {136},
number = {25},
pages = {254001},
doi = {10.1103/z1hs-ydjc},
pmid = {42430608},
issn = {1079-7114},
abstract = {We study phase-separating fluid mixtures as they demix in the presence of chemical reactions that maintain them away from thermodynamic equilibrium. We show that in such chemically active emulsions the interplay of chemical reactions, phase separation, and hydrodynamics effects complex self-organization and pattern formation that can give rise to spatiotemporal chaos. This chaotic dynamics, unlike in classical turbulence, is not due to fluid inertia-we analyze the system in the Stokes flow regime-and it is different from the turbulence of active nematics at low Reynolds number, for our fluid mixtures lack any orientational order. To explore the generic features of nonlinear dynamics in our system, we derive amplitude equations which we find to be identical to those obtained for Rayleigh-Benard convection with mean flow and stress-free conditions at the top and bottom plates. Chemically active emulsions possessing no internal order, we thus establish, can exhibit chaoticity that is driven by interfacial stresses in the fluid mixture.},
}

@article {pmid42414385,
year = {2026},
author = {Rehman, A and Fahs, M and Baalousha, HM},
title = {Scale dependent Forchheimer flow in bioturbated limestone characterised by CT imaging and multi scale CFD analysis.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-60034-7},
pmid = {42414385},
issn = {2045-2322},
abstract = {Bioturbation is the reworking of sediments by organisms, which can significantly modify the petrophysical properties of aquifers by introducing burrow-related macro-porosity and enhanced pore connectivity. Many sedimentary formations worldwide contain bioturbated intervals interbedded with less permeable or impermeable strata. Likewise, the Aruma Formation on the Arabian Shelf contains intervals of bioturbated strata with large, open centimetre-scale burrows. Although the geometric characterisation of these burrow networks is well documented, groundwater flow modelling in these aquifers remains poorly understood. The formation contains intervals of intensely bioturbated limestone characterised by large, open, and well-connected burrows, providing an ideal natural analogue to investigate flow behaviour in such systems. This study presents an integrated approach combining high-resolution computed tomography (CT) scans with multi-scale computational fluid dynamics (CFD) modelling to investigate groundwater flow in a bioturbated limestone sample. First, three-dimensional models of connected burrow networks were reconstructed from CT scan images at three different scales. The steady-state single-phase flow was simulated using the Darcy's Law and the Laminar Flow (Navier-Stokes) interfaces in COMSOL Multiphysics. The Darcy interface results yielded constant permeability values with a linear velocity-pressure relationship across all three scale models, whereas the Laminar Flow results showed strong nonlinearity and yielded varying permeability values across the tested pressure range. High Reynolds number values were observed in the Laminar Flow results, reaching approximately 355 for the small model, 111 for the intermediate model, and 123 for the large model. These results suggest that inertial effects arise at very low driving pressures due to flow concentration within centimetre-scale burrow networks. Forchheimer analysis provided an excellent fit to the simulated data (R[2] ≥ 0.99), confirming that flow is governed by combined viscous and inertial losses rather than by purely viscous behaviour. This study demonstrates that bioturbation altered the hydraulic properties of a limestone rock by creating burrow-dominated systems in which Darcy's law is not applicable. The findings also highlight the need to incorporate non-linear flow formulations into groundwater and reservoir models for bioturbated samples and to provide a robust framework for linking pore-scale geometry to flow behaviour in heterogeneous systems.},
}

@article {pmid42414510,
year = {2026},
author = {Tsuzuki, S},
title = {Curvature-weighted spectra anticipate dissipation peaks in decaying three-dimensional turbulence.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-61148-8},
pmid = {42414510},
issn = {2045-2322},
support = {22K14177//Japan Society for the Promotion of Science/ ; JPMJPR23O7//Precursory Research for Embryonic Science and Technology/ ; },
abstract = {We investigate the robustness of a curvature-weighted spectral precursor to dissipation in freely decaying three-dimensional incompressible turbulence. Building on our recent work in Physical Review Fluids on the Taylor-Green vortex, we analyze direct numerical simulations using the shell-summed curl-of-vorticity spectrum, denoted here by [Formula: see text] and equivalent to a [Formula: see text]-weighted energy spectrum in the modal incompressible sense. Extending the study across multiple initial conditions-multi-mode ABC flows, a randomized low-wavenumber ABC field, the Taylor-Green vortex, and the Kida-Pelz flow-we find a consistent temporal ordering: the characteristic time associated with the advance and saturation of the peak wavenumber of [Formula: see text] precedes the dissipation-peak time, which in turn precedes the characteristic time associated with the peak scale of the nonlinear energy-flux spectrum. We further probe Reynolds-number and scale-separation effects using Taylor-Green simulations at additional viscosities: the precursor ordering persists when adequate scale separation and resolution are maintained, but can change in the low-[Formula: see text]/limited-scale-separation regime. Throughout, we use explicit inspection of curvature-weighted spectra to distinguish physical peak evolution from cutoff-proximate artifacts. These results support robustness over the deterministic decaying-flow initial conditions examined here and clarify the practical role of Reynolds number, scale separation, and resolution when using curvature-weighted spectral diagnostics in decaying turbulence.},
}

@article {pmid42401719,
year = {2026},
author = {Jafari, B and Hosseinzadeh, K and Mehrzad, A and Mohammadzadeh, AM},
title = {Performance enhancement of a wavy microchannel heat sink by geometric modification and porous copper foam integration.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-61054-z},
pmid = {42401719},
issn = {2045-2322},
abstract = {Rising heat flux in compact electronics demands advanced microchannel cooling with enhanced heat transfer and minimal pressure drop penalties. This study provides a comprehensive assessment of the coupled effects of microchannel geometry, porous-medium characteristics, and operating conditions on the thermo-hydraulic performance of a porous-foam-enhanced wavy microchannel heat sink. A three-dimensional computational fluid dynamics (CFD) model was developed and the governing mass, momentum, and energy equations were solved using the finite volume method. The porous copper foam was modeled as a homogeneous porous medium under the local thermal equilibrium (LTE) assumption. The thermo-hydraulic characteristics of a microchannel with wavy surfaces featuring cubic obstacles and copper foam have been studied through three different parameters: geometry (ratio of the height of the porous layer on the walls and the ratio of the height of the porous layer on the rib, varying from 0.1 to 0.9), microstructure of the material (copper foams with various porosity, permeability, and pore density), and operating conditions (Reynolds number from 100 to 900 and inlet temperature from 293 to 301 K). Results demostrate that the combination of an increase in both the height of the obstacle and the thickness of the porous material of the wall improves heat transfer. The comparison between 0.1/0.1 and 0.5/0.9 configurations indicate that the Nusselt number rises by 96%, while the highest temperature decreases by 1.6%. On the other hand, the friction factor is increased. In terms of operating conditions, increasing the Reynolds number from 100 to 900 boosts Nusselt by 108% and reduces friction by 58%; Re = 800 acts as a knee point, achieving 95% of the maximum PEC with 18-21% lower pressure drop than Re = 900. For Re = 600, an increase in the inlet temperature from 293 to 301 K leads to a relatively moderate improvement in terms of thermal efficiency. Indeed, in such conditions, the Nusselt number is increased by 1.3%, and the friction factor is decreased by 7.2%, leading to the PEC being improved by 3.86%. Therefore, the inlet temperature equal to 301 K provides a more effective thermo-hydraulic performance in the considered case. In general, the obtained data prove the fact that using porous copper foam in wavy microchannel with flow obstacles leads to the improvement of heat transfer in electronic devices. As this process is accompanied by increasing fluid mixing and heat transfer surface, the achieved result is positive considering the acceptable hydraulic losses.},
}

@article {pmid42380499,
year = {2026},
author = {Sultan, AJ and Yahya, AA and Faraj, FH and Singh, NSS and Jasim, DJ and Sabri, LS and Aljaafari, HAS and Taner, M and Hasanabad, AM},
title = {Numerical modeling of the hydrodynamic behavior of MgO-water nanofluid in plate-fin heat exchangers under varying operating conditions.},
journal = {Scientific reports},
volume = {},
number = {},
pages = {},
doi = {10.1038/s41598-026-60276-5},
pmid = {42380499},
issn = {2045-2322},
abstract = {This research examined the ability of an artificial neural network to predict flow behavior, defined by Reynolds number and pressure drop as functions of volume fraction and temperature, at fixed flow rates of 5, 8, and 11 LPM. The proposed framework was developed to address the nonlinear, interrelated thermo-compositional effects that influence flow inertia and pressure losses, without relying on predefined empirical relationships. The model's reliability and predictive performance were evaluated through 5-fold cross-validation, monitoring of learning errors, regression diagnostics, error quantification, and sensitivity analysis. Results from cross-validation indicated stable Reynolds number predictions at low and moderate flow rates, with mean RMSE values of 6.39 at 5 LPM and 6.16 at 8 LPM. At 11 LPM, the mean RMSE rises to 13.87, highlighting the greater sensitivity and complexity of inertia-dominated flow regimes. Conversely, predictions of pressure drop remained consistently accurate across all operating conditions, achieving mean RMSE values of 2.68 mbar, 0.56 mbar, and 0.94 mbar at 5, 8, and 11 LPM, respectively. Regression analysis confirmed a strong linear relationship between predicted and reference values for both outputs, with correlation coefficients exceeding 0.99 at low and moderate flow rates and remaining above 0.96 at the highest flow rate. Further analysis of relative and absolute errors indicated high predictive accuracy, with mean relative errors below 5% for Reynolds number and below 1.3% for pressure drop across all scenarios. Sensitivity analysis consistently identified temperature as the primary source of predictive variability, with volume fraction being the secondary contributor. Pressure drop showed significantly lower sensitivity than Reynolds number, suggesting a smoother, less nonlinear relationship with the governing inputs.},
}

@article {pmid42377817,
year = {2026},
author = {Akbar, NS and Saleem, N and Akram, J and Eressa, LA and Muhammad, T and Hussain, MF and Habib, MB},
title = {Thermal irreversibility and entropy generation analysis in MHD peristaltic transport of blood-based hybrid nanofluid through a curved duct.},
journal = {Discover nano},
volume = {21},
number = {1},
pages = {},
pmid = {42377817},
issn = {2731-9229},
support = {RGP.2/435/45.//Deanship of Research and Graduate Studies at King Khalid University, KSA/ ; },
abstract = {The thermal control of peristaltic blood flow in a curved duct under a magnetic field is a relatively unexplored phenomenon. This research fills this gap by proposing the use of a blood-based hybrid nanofluid. The blood flow is assumed to be a non-Newtonian fluid, modelled by the Casson fluid model. It is mixed with gold (20 nm) and iron oxide (25 nm) nanoparticles. The equations are expressed in a cylindrical coordinate system in order to account for the curved nature of the duct. Peristaltic waves are considered to propagate along the wall. The governing equations are obtained using the low Reynolds number approximation (Reynolds number Re) and long wavelength approximation. The finite element method (FEM) with Python programming is applied for solving the resulting strongly nonlinear partial differential equations. The obtained results are also utilized to analyze the irreversibility of the system. The main findings indicate that increasing the aspect ratio enhances the blood flow velocity at the central part. It is found that the mono nanofluid has more improvement in central velocity compared to the hybrid nanofluid. Optimal control of the magnetic parameter and duct wall elasticity can enhance the flow efficiency. It also results in a reduction of thermal losses and thermodynamic irreversibilities.},
}

@article {pmid42378293,
year = {2026},
author = {Cheng, S and Das, D and Barchuk, M and Armstrong, R and Klingbeil, MM and Thomases, B and Zhou, S},
title = {Corkscrew motion of Trypanosoma brucei is driven by helical beating of the flagellum and facilitated by its bent shape.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {123},
number = {27},
pages = {e2536746123},
doi = {10.1073/pnas.2536746123},
pmid = {42378293},
issn = {1091-6490},
support = {2239551//NSF | MPS | Division of Materials Research (DMR)/ ; NA//Donald P. Reed Legacy Fund/ ; },
mesh = {*Trypanosoma brucei brucei/physiology ; *Flagella/physiology ; Hydrodynamics ; Models, Biological ; Cell Movement/physiology ; Cell Shape/physiology ; },
abstract = {In the pathogenic parasite Trypanosoma brucei, a laterally attached flagellum drives rapid deformation of the complex cell body, producing puzzling dynamics. High-speed defocusing imaging reveals that surface points trace flower-like patterns in transverse planes. The petals arise from clockwise flagellar beating, which generates a right-handed helical wave propagating from the anterior tip along the body, advancing the cell like a twisted corkscrew. The central lobes result from slower counterclockwise body rotation required to balance the active torque. The bent cell shape underneath the flagellum superimposes these two chiral motions at different radial distances, producing the observed patterns. Three-dimensional hydrodynamic simulations using the method of regularized Stokeslets reproduce these dynamics and show that bent cell shape enhances swimming, suggesting an adaptive advantage of T. brucei's morphology.},
}

*Trypanosoma brucei brucei/physiology
*Flagella/physiology
Hydrodynamics
Models, Biological
Cell Movement/physiology
Cell Shape/physiology