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1
Content available remote Electrokinetics of Dielectric Non-Newtonian Bio Fluids with Heat Transfer Through a Flexible Channel : Numerical Study
100%
Mekheimer K. S. , Hasona W. M. , El-Shekhipy A. A. , Zaher A. Z.
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tom Vol. 23, No. 4
331--341
EN
Throughout this paper we investigate the effect of a vertical alternative current AC and heat transfer on the peristaltic flow of a couple stress dielectric fluid (blood flow model) in a symmetric flexible sinusoidal wavy channel. In order to solve the system of coupled non-linear partial differential equations, a program designed by Mathematica software "parametric NDSolve package" is used, which pertains to describe the momentum, the energy, and the electric potential that is obtained from using a regular perturbation method with small amplitude ratio. The numerical formulas of the mean velocity, the mean temperature, and the mean electric field are computed and the phenomenon of reflux (the mean flow reversal) is discussed. Moreover, the physical parameters effects of the problem on these formulas are described and illustrated graphically. The results reveal that the mean time averaged velocity is accelerated in the presence of AC electric field and decelerated for the couple stress fluid model (a special case of non-Newtonian fluid). The mean time averaged temperature is high in the presence of an alternative current AC electric field. This results model imply that the physiological role of AC electric field enhances blood circulation and this might help to eliminate the metabolic waste products and endogenous pains producing.
2
Content available remote Steady streaming effect on the flow of a couple stress fluid through a constricted annulus
100%
Srinivasacharya D. , Srikanth D.
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tom Vol. 64, nr 2
137-137
EN
The oscillatory flow of an incompressible couple stress fluid through an annulus with mild constriction at the outer wall is considered. The mean pressure drops and the mean wall shear stress are calculated across the constricted region. The steady streaming effect on the flow is presented. The variations in the mean pressure drop and wall shear stress with the size of the catheter, the velocity of the catheter and couple stress fluid parameter, are studied through graphs.
3
Content available remote Flow and heat transfer of a quadratic stretching sheet in a Boussinesq-Stokes suspension
86%
Sekhar G. N. , Chethan A. S.
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tom Vol. 16, no 4
1109-1128
EN
An analysis is carried out to study the flow and heat transfer in a couple stress fluid over a stretching sheet. The velocity of the sheet is taken as a quadratic polynomial of the distance from the sheet. This results in the manifestation of augmentation of flow in the direction transverse to the sheet. An analytical expression is obtained for velocity components as a function of the couple stress parameter and stretching related parameters. The heat transfer characteristic of a Boussinesq-Stokes suspension over a continuous stretching surface with internal heat generation/absorption is analyzed. Two cases are studied, namely (i) the sheet with prescribed surface temperature (PST-case) and (ii) the sheet with prescribed heat flux (PHF-case). The basic boundary layer equations for momentum and heat transfer, which are non-linear partial differential equations, are converted into non-linear ordinary differential equations by means of similarity transformation. The resulting non-linear differential equation is solved exactly. The solution and heat transfer characteristics are obtained in terms of Kummer's functions. The results have possible technological applications in the liquid-based systems involving stretchable materials.
4
Free convection effects on a perfectly conducting couple stress fluid
86%
Ezzat M. , Zakaria M. , Samaan A. , Abd-el Bary A.
Journal of Technical Physics
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2006
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tom Vol. 47, no 1
5-30
EN
We have introduced a magnetohydrodynamic model of boundary-layer equations for a perfectly conducting couple-stress fluid. This model is applied to study the effects of free convection currents with thermal relaxation on the flow of a polar fluid through a porous medium, which is bounded by a vertical plane surface. The state space formulation developed in EZZAT [1] and [2j is introduced. The formulation is valid for problems with or without heat sources. The resulting formulation, together with the Laplace transform technique, are applied to a variety of problems. The solution to a thermal shock problem and to the problem of the flow in the whole space with a plane distribution of heat sources are obtained. It is also applied to a semispace problem with a plane distribution of heat sources located inside the fluid. A numerical method is employed for the inversion of the Laplace transforms. The effects of Grashof number, material parameters, Alfven velocity, relaxation time, Prandtl number and the permeability parameter on the velocity, the temperature and the angular velocity distributions are discussed. The effects of cooling and heating of a couple-stress fluid have also been discussed. Numerical results are given and illustrated graphically for the problems considered.
5
Content available Slow flow of couple stress fluid past a cylinder embedded in a porous medium: slip effect
86%
Sarkar P. , Madasu K. P.
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2023
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tom Vol. 71, iss. 4
537--551
EN
An analytical study for the creeping flow of a couple stress fluid past a cylinder embedded in a porous medium is presented using the slip condition. The uniform flow is considered far away from a cylinder. The boundary conditions used are zero couple stress and tangential slip conditions. The modified Bessel functions represent the stream function (the velocity). The drag exerted on a solid cylinder immersed in a porous medium is derived. The impacts of the couple stress, permeability, and slip parameters on the normalized drag force are presented graphically. The drag forces of well-known exceptional cases are reduced. The drag force is a decreasing function of the permeability and couple stress parameters and an increasing function of the slip parameter.
6
Content available Mixed convective flow of unsteady hydromagnetic couple stress fluid through a vertical channel filled with porous medium
86%
Makhalemele C. R. , Rundora L. , Adesanya S. O.
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tom Vol. 25, no. 4
148--161
EN
In this paper, the mixed convective flow of an electrically conducting, viscous incompressible couple stress fluid through a vertical channel filled with a saturated porous medium has been investigated. The fluid is assumed to be driven by both buoyancy force and oscillatory pressure gradient parallel to the channel plates. A uniform magnetic field of strength 0B is imposed transverse to the channel boundaries. The temperature of the right channel plate is assumed to vary periodically, and the temperature difference between the plates is high enough to induce radiative heat transfer. Under these assumptions, the equations governing the two-dimensional couple stress fluid flow are formulated and exact solutions of the velocity and the temperature fields are obtained. The effects of radiation, Hall current, porous medium permeability and other various flow parameters on the flow and heat transfer are presented graphically and discussed extensively.
7
Content available remote Pressure distribution in a squeeze film biobearing lubricated by a synovial fluid
86%
Jurczak P.
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tom Vol. 11, no 4
857-864
EN
The flow of a synovial fluid in a squeeze film biological bearing is considered. The biobearing is modelled by two rotational surfaces and the porous layer is adheres to the curved non-porous surface. The flow in the biobearing clearance is considered with inertia and the Navier-Stokes and Poisson equations are uncoupled by using the Morgan-Cameron approximation. As an example the biobearing modelled by two disks and two spherical surfaces is discussed.
8
Content available remote Influence of rheological parameters on the mechanical parameters of curvilinear thrust bearing with one porous wall lubricated by a couple stress fluid
86%
Jurczak P. , Walicka A. , Walicki E. , Michalski D.
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tom Vol. 11, no 2
221-233
EN
The flow of a couple stress fluid in the clearance of a curvilinear thrust bearing with a porous pad is considered. The porous pad is connected with an upper impermeable rotating surface which approaches the lower fixed bearing surface. The Reynolds and Poisson equations are uncoupled by using the Morgan-Cameron approximation and a closed-form solution is obtained. Expressions for the pressure and capacity load of the bearing are given. As an example the bearing modelled by two disks and two spherical surfaces is discussed.
9
Content available remote Global stability for thermal convection in a couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity
72%
Sunil , Chodhary S. , Bharti P. K.
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2012
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tom Vol. 17, no. 2
583-602
EN
We show that the global nonlinear stability threshold for convection in a couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that the linearized instability theory has captured completely the physics of the onset of convection. Then the effect of couple stress parameter, variable dependent viscosity and Darcy-Brinkman number on the onset of convection are also analyzed.
10
Content available remote Combined effect of magnetic field and rotation on thermal stability of a couple-stress fluid heated from below in the presence of suspended particles
72%
Aggarwal A. K. , Makhija S.
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tom Vol. 16, no 4
931-942
EN
Thermal stability of a couple-stress fluid in the presence of suspended particles, magnetic field and rotation is considered. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For stationary convection, it is found that suspended particles have a destabilizing effect whereas rotation has a stabilizing effect. The magnetic field and couple-stresses have a stabilizing effect under certain conditions. In the absence of rotation, couple-stresses and magnetic field have a stabilizing effect on the system. It is found that the principle of exchange of stabilities is satisfied in the absence of the magnetic field.
11
Content available remote Stability of superposed viscous - viscoelastic (couple-stress) fluids in the presence of variable magnetic field through porous medium
72%
Kumar P. , Sharma P.
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2008
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tom Vol. 13, no 3
837-845
EN
The Rayleigh-Taylor instability of a Newtonian viscous fluid overlying a couple-stress viscoelastic fluid through a porous medium is considered in the presence of a variable horizontal magnetic field. The stability analysis is carried out, for mathematical simplicity, for two highly viscous fluids of equal kinematic viscosities. For the stable configuration, the system is found to be stable or unstable under certain conditions. However, for the unstable configuration, the magnetic field has got stabilizing effects.
12
Content available Couple stress fluid past a sphere embedded in a porous medium
72%
Madasu K. P. , Sarkar P.
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tom LXIX, nr 1
5--19
EN
This paper concerns the analytical investigation of the axisymmetric and steady flow of incompressible couple stress fluid through a rigid sphere embedded in a porous medium. In the porous region, the flow field is governed by Brinkman’s equation. Here we consider uniform flow at a distance from the sphere. The boundary conditions applied on the surface of the sphere are the slip condition and zero couple stress. Analytical solution of the problem in the terms of stream function is presented by modified Bessel functions. The drag experienced by an incompressible couple stress fluid on the sphere within the porous medium is calculated. The effects of the slip parameter, the couple stress parameter, and permeability on the drag are represented graphically. Special cases of viscous flow through a sphere are obtained and the results are compared with earlier published results.
13
Content available remote Flow of a couple-stress fluid in a curvilinear thrust bearing with one porous pad
72%
Jurczak P. , Walicka A. , Walicki E. , Michalski D.
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tom nr 3
63-75
EN
The flow of a couple stress fluid in the clearance of a curvilinear bearing with a porous pad is considered. The porous pad is connected with the upper impermeable rotating surface which approaches the lower fixed bearing surface. The Reynolds and Poisson equations are uncoupled by using the Morgan-Cameron approximation and a closed-form solution is obtained. As an example the bearing formed by two disks is discussed.
PL
W pracy rozważono przepływ płynu z naprężeniami momentowymi w krzywoliniowej szczelinie łożyska z porowatą wkładką. Porowata wkładka powiązana jest z górną nieprzepuszczalną wirującą powierzchnią, która zbliża się do dolnej nieruchomej powierzchni łożyska. Do rozwiązania równań Poissona oraz Reynoldsa wykorzystano przybliżenie Morgana-Camerona. Jako przykład rozpatrzono łożysko utworzone przez dwie kołowe tarcze.
14
Content available Review of applied mathematical models for describing the behaviour of aqueous humor in eye structures
58%
Dzierka M. , Jurczak P.
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tom Vol. 20, no. 4
757--772
EN
In the paper, currently used methods for modeling the flow of the aqueous humor through eye structures are presented. Then a computational model based on rheological models of Newtonian and non-Newtonian fluids is proposed. The proposed model may be used for modeling the flow of the aqueous humor through the trabecular meshwork. The trabecular meshwork is modeled as an array of rectilinear parallel capillary tubes. The flow of Newtonian and non-Newtonian fluids is considered. As a results of discussion mathematical equations of permeability of porous media and velocity of fluid flow through porous media have been received.
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