scholarly journals SWIMMING DYNAMICS OF A MICRO-ORGANISM IN A COUPLE STRESS FLUID: A RHEOLOGICAL MODEL OF EMBRYOLOGICAL HYDRODYNAMIC PROPULSION

2017 ◽  
Vol 17 (03) ◽  
pp. 1750054 ◽  
Author(s):  
N. ALI ◽  
M. SAJID ◽  
Z. ABBAS ◽  
O. ANWAR BÉG
Keyword(s):  
Swimming Speed ◽  
Couple Stress ◽  
Fluid Model ◽  
Lateral Displacement ◽  
Structural Characteristics ◽  
Couple Stress Fluid ◽  
Fluid Medium ◽  
Fluid Parameter ◽  
Work Done ◽  
Perturbation Solutions

Mathematical simulations of embryological fluid dynamics are fundamental to improving clinical understanding of the intricate mechanisms underlying sperm locomotion. The strongly rheological nature of reproductive fluids has been established for a number of decades. Complimentary to clinical studies, mathematical models of reproductive hydrodynamics provide a deeper understanding of the intricate mechanisms involved in spermatozoa locomotion which can be of immense benefit in clarifying fertilization processes. Although numerous non-Newtonian studies of spermatozoa swimming dynamics in non-Newtonian media have been communicated, very few have addressed the micro-structural characteristics of embryological media. This family of micro-continuum models include Eringen’s micro-stretch theory, Eringen’s microfluid and micropolar constructs and V. K. Stokes’ couple stress fluid model, all developed in the 1960s. In the present paper we implement the last of these models to examine the problem of micro-organism (spermatozoa) swimming at low Reynolds number in a homogenous embryological fluid medium with couple stress effects. The micro-organism is modeled as with Taylor’s classical approach, as an infinite flexible sheet on whose surface waves of lateral displacement are propagated. The swimming speed of the sheet and rate of work done by it are determined as function of the parameters of orbit and the couple stress fluid parameter ([Formula: see text]). The perturbation solutions are validated with a Nakamura finite difference algorithm. The perturbation solutions reveal that the normal beat pattern is effective for both couple stress and Newtonian fluids only when the amplitude of stretching wave is small. The swimming speed is observed to decrease with couple stress fluid parameter tending to its Newtonian limit as alpha tends to infinity. However the rate of work done by the sheet decreases with [Formula: see text] and approaches asymptotically to its Newtonian value. The present solutions also provide a good benchmark for more advanced numerical simulations of micro-organism swimming in couple-stress rheological biofluids.

PERISTALTIC FLOW OF COUPLE-STRESS FLUID WITH HEAT AND MASS TRANSFER: AN APPLICATION IN BIOMEDICINE

2015 ◽  
Vol 15 (04) ◽  
pp. 1550042 ◽  
Author(s):  
S. HINA ◽  
M. MUSTAFA ◽  
T. HAYAT ◽  
A. ALSAEDI
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Couple Stress ◽  
Amplitude Ratio ◽  
Circulatory System ◽  
Particle Size Effect ◽  
Couple Stress Fluid ◽  
Electrically Conducting ◽  
Fluid Parameter ◽  
Compliant Walls

Analysis is performed for the simultaneous effects of heat and mass transfer on the peristaltic transport of an electrically conducting couple-stress fluid in a compliant walls channel. The study may be useful in understanding the physiological flow of blood through micro-circulatory system in the presence of particle-size effect. Long wavelength and low Reynolds number aspects are taken into consideration. Exact solutions for stream function, temperature and concentration are derived. Impact of pertinent parameters like the couple-stress fluid parameter (γ), Hartman number (M), amplitude ratio (ϵ), elastic parameters (E1, E2, E3, E4, E5), Brinkman number (Br) and Schmidt number (Sc). It is observed that velocity and temperature distributions are greater for couple stress fluid when compared with the Newtonian fluid.

scholarly journals Performance Characteristics of a Long Porous Partial Journal Bearing using Couple Stress Fluid

2019 ◽  
Vol 8 (4) ◽  
pp. 4235-4240
Keyword(s):  
Flow Rate ◽  
Couple Stress ◽  
Journal Bearing ◽  
Fluid Model ◽  
Performance Characteristics ◽  
Fluid Film ◽  
Couple Stress Fluid ◽  
Squeeze Film ◽  
Stress Parameter ◽  
Matlab Programming

After effects of studies led on a long porous partial journal bearing for couple stress fluid are thus displayed. Performance characteristics presently determined incorporate the time-height relationship, Fluid film force, Flow rate, frictional force alongside the coefficient of friction. Plan/Technique/Approach -The paper shows a solution for the squeeze film lubrication of a thick, porous, with couple stress fluid model. It is determined that the changed Reynolds condition inferred the fluid film pressures. The modified state of Reynolds equation is analytically solved and closed form expressions are shown for the time-height, the flow rate and friction force with frictional coefficient numerically with the given starting condition using MATLAB programming, the first non-linear equation in the time-height relationship is resolved. The effects on the squeeze film characteristics of couple stresses and permeability are discussed. Findings – It can be seen that the couple stress parameter enhances the bearing characteristics. The bearing performance can be improved with the increase of couple stress parameter ( l  ), eccentricity ratio (ϵ), permeability parameter (ψ). Additional study may be performed using the couple stress fluid model, including the magnetic effect with heat and mass transfer. This model can be used to compare further with other models such as micropolar fluid, rabinowitsch fluid and for comparative study, which models are the most suitable for improving bearing system performance.

Linear stability analysis of long journal bearings: couple stress fluid model

2005 ◽  
Vol 57 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Won‐Hsion Liao ◽  
Rong‐Fang Lu ◽  
Rean‐Der Chien ◽  
Jaw‐Ren Lin
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Couple Stress ◽  
Fluid Model ◽  
Journal Bearings ◽  
Couple Stress Fluid

scholarly journals Swirling flow of couple stress fluid due to a rotating disk

2019 ◽  
Vol 8 (1) ◽  
pp. 261-269 ◽  
Author(s):  
Najeeb Alam Khan ◽  
Nadeem Alam Khan ◽  
Saif Ullah ◽  
Farah Naz
Keyword(s):  
Differential Equations ◽  
Couple Stress ◽  
Swirling Flow ◽  
Nonlinear Differential Equations ◽  
Rotating Disk ◽  
Tangential Component ◽  
Couple Stress Fluid ◽  
Governing System ◽  
Fluid Parameter ◽  
Homotopy Analysis

AbstractThe main objective of the present investigation is to examine the couple stress fluid flow occurring as a result of rotation of a disk. On implementing a suitable transformation, the governing system of partial differential equations (PDEs) is converted into nonlinear differential equations of a single independent variable. These equations are solved analytically by virtue of the Homotopy Analysis Method (HAM) which gives solutions in the form of a series. The solution of most of the governing problems is determined in terms of the absolute exponential and decaying functions by means of this powerful technique. To support analytic results, some graphs are plotted for determining the convergence of the solution. Also the graphical interpretation of velocity profiles corresponding to the effects of pertinent parameters are shown and discussed in detail. The numerical results are calculated for evaluation of the influence of fluid parameter. It can also be anticipated that the radial and axial velocity components show decreasing behavior due to rise in the values of couple stress parameter which conflict the behavior of the tangential component of velocity.

COUPLE STRESS FLUID MODEL FOR PULSATILE FLOW OF BLOOD IN A POROUS TAPERED ARTERIAL STENOSIS UNDER MAGNETIC FIELD AND PERIODIC BODY ACCELERATION

2017 ◽  
Vol 17 (08) ◽  
pp. 1750109 ◽  
Author(s):  
R. PONALAGUSAMY ◽  
S. PRIYADHARSHINI
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Newtonian Fluid ◽  
Couple Stress ◽  
Flow Resistance ◽  
Fluid Model ◽  
Arterial Stenosis ◽  
Couple Stress Fluid ◽  
Flow Through ◽  
Wall Shear

In this paper, a magnetic and non-Newtonian fluid model for pulsatile flow of blood with periodic body acceleration has been investigated by adopting Laplace transform and finite Hankel transform. A closed form of analytic solution is obtained for physiologically important quantities such as velocity profile, flow rate, wall shear stress and flow resistance. Effects of different physical parameters reflecting couple stress parameter, Darcy number, Hartman number, tapering angle (divergent tapered tube or convergent tapered tube), shape stenosis parameter and amplitude of periodic acceleration on wall shear stress and flow resistance have been emphasized. For any value of taper angle ([Formula: see text]) and stenotic height ([Formula: see text]), it is pertinent to point out here that the wall shear stress is less in the case of flow through the asymmetric stenosed tube as compared to the case of flow through the symmetric stenosed tube when one is in the up-stream of flow region, but it is of opposite behavior as one moves in the down-stream of flow region. It is important to note that the flow resistance increases significantly and more nonlinearly with the increase in the axial distance in the case of flow through a converging tapered artery with stenosis as compared to that of the same flow through a stenosed artery. The size of trapping bolus becomes larger for the flow of couple stress fluid through a converging tapered arterial stenosis than that of the same flow through a stenosed artery. Another important result is that as compared to the case of Newtonian fluid, the couple stress fluid behaviour plays a key role in increasing the size of trapping bolus. This investigation puts forward important observations that the asymmetric nature of stenosis considered plays a predominant role in reducing the flow resistance in the case of diseased blood vessel and the flow resistance is higher for the case of couple stress fluid than that of Newtonian fluid. Finally, some applications of the present model have been briefly discussed.

Biomathematical study of Sutterby fluid model for blood flow in stenosed arteries

2015 ◽  
Vol 08 (06) ◽  
pp. 1550075 ◽  
Author(s):  
Noreen Sher Akbar
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Fluid Model ◽  
Cylindrical Geometry ◽  
Mild Stenosis ◽  
Fluid Parameter ◽  
Wall Shear ◽  
Parameters Of Interest ◽  
Perturbation Solutions

In this paper, we have discussed the biomathematical analysis of Sutterby fluid model for blood flow in stenosed tapered arteries. The equations for the Sutterby fluid model are modeled in cylindrical geometry. The equations have been developed for the case of mild stenosis. Perturbation solutions are attained in terms of small Sutterby fluid parameter β for the velocity, impedance resistance and wall shear stress. Three types of arteries i.e. converging, diverging and non-tapered have been considered for the analysis and discussion. Graphical results have been presented for different parameters of interest. Streamlines have been plotted at the end of the paper.

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