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1
Content available Heat flow through a thin cooled pipe filled with a micropolar fluid
100%
Beneš M. , Pažanin I. , Suárez-Grau F. J.
Journal of Theoretical and Applied Mechanics
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2015
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tom Vol. 53 nr 3
569--579
EN
In this paper, a non-isothermal flow of a micropolar fluid in a thin pipe with circular cross- -section is considered. The fluid in the pipe is cooled by the exterior medium and the heat exchange on the lateral part of the boundary is described by Newton’s cooling condition. Assuming that the hydrodynamic part of the system is provided, we seek for the micropolar effects on the heat flow using the standard perturbation technique. Different asymptotic models are deduced depending on the magnitude of the Reynolds number with respect to the pipe thickness. The critical case is identified and the explicit approximation for the fluid temperature is built improving the known result for the classical Newtonian flow as well. The obtained results are illustrated by some numerical simulations.
2
Content available remote The concept of a quasi-micropolar fluid model
100%
Szubartowski D. , Ganczarski A.
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2016
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tom Y. 113, iss. 1-M
224--230
EN
This paper presents a micropolar fluid model that direct applies Cosserat’s continuum to hydrodynamics. The corresponding system of equations describing isotropic micropolar fluid is obtained by assuming lack of symmetry of the Cauchy stress tensor and taking into account the conservation of angular momentum. This turns out to be an extension of the NavierStokes fluid but containing turbulent effect built in.
PL
W artykule przedstawiono mikropolarny model cieczy stanowiący bezpośrednie zastosowanie kontinuum Cosseratów w hydromechanice. Zakładając brak symetrii tensora naprężenia Cauchy’ego oraz uwzględniając zasadę zachowania momentu pędu otrzymano układ równań opisujący izotropową ciecz mikropolarną. Układ równań jest uogólnieniem równań NavieraStokesa poprzez uwzględnienie efektu turbulentnego.
3
Heat transfer from a stretching surface in a micropolar fluid
100%
El-Hakiem M. A. , Mohammadein A. A. , Mansour M. A. , Gorla R. S. R.
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tom Vol. 4, no 1
25-34
EN
The theory of micropolar fluids due to Eringen is used to formulate a set of boundary layer equations for the heat transfer from an arbitrarily stretching surface with non-uniform surface temperature. A two dimensional similarity solution to the governing momentum, angular momentum and energy equations is presented. The effects of the boundary conditions used for the microrotation term are discussed. Numerical data for the friction factor and Nusselt number has been shown graphically for a range of values of the material properties.
4
Content available remote Slow motion of a rotating circular cylinder through a micropolar fluid
100%
Moosaie A. , Atefi G.
Archives of Mechanics
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2008
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tom Vol. 60, nr 3
199-220
EN
Presented is an analytical solution to creeping flow of a micropolar fluid past a rotating circular cylinder of infinite length in spanwise direction. The solution is decomposed into two parts; first, the flow past a stationary circular cylinder is solved by the use of matched asymptotic expansions method. Afterwards, the rotation of a circular cylinder in a stationary ocean of a micropolar fluid is investigated. Due to linearity of the governing equations, the principle of superposition is then recalled to construct the desired flow field. Ultimately, several kinematic and kinetic quantities of the flow are studied by the use of the obtained closed-form analytical solution.
5
Content available Flow past a sphere moving towards a wall in micropolar fluid
100%
Kucaba-Piętal A.
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tom nr 2
301-318
EN
The paper presents the first "exact" solution to the problem of creeping flow past a sphere mowing towards a wall in micropolar fluid. The analytical-numerical method is presented, that is a development of the boundary collocation technique previously used for solving many corresponding problems for a Newtonian fluid. The initial study of the method has been carried out and the results for a force acting on a sphere compared with their counterparts for a Newtonial fluid are presented. It is worth while to note that the drag force on a sphere depends on material constants of the micropolea fluid and the distance from the wall.
PL
Rozwiązane zostało zagadnienie wyznaczenia pola przepływu i działającej siły na cząstkę kulistą poruszającą się w kierunki ścianki w płynie mikropolarnym. Skonstruowano metodę analityczno-- --numeryczną w oparciu o metodę kolokacji. Rozpatrzono przepływ quasistacjonarny w przybliżeniu Stokesa.
6
Content available Modelling of lubrication mechanism in human joints using micropolar fluid theory
100%
Kucaba-Piętal A.
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tom nr 3
593-606
EN
The paper aims at presentation of modelling of human joints withinthe framework micropolar fluid theory. A mathematical model of two converging spheres represents the biobearings. In the model the boundaries of the spheres are considered to be rigid and the lubricant (synovial fluid) is represented by a micropolar fluid. Basing on the asymptotic solution obtained for squeezing motion of converging spheres (Kucaba-Piętal, 1999), the velocity vector in a gap is determined and asymptotic values of the forceare calculated. The effects or rheological constants variation on the flow field in a gap are disscussed.
PL
Przedmiotem pracy jest opis smarowania w stawach na bazie teorii płynów mikropolarnych. Rozpatrywany jest ruch ciśnieniowy (squeezing). Staw (biodrowy) modelowany jest za pomocą układu dwóch kul o twardych powierzchniach. Zakłada się, że przepływ opisany jest równaniem Stokesa. Na bazie rozwiązania asymptotycznego obliczono rozkład prędkości w szczelinie stawowej oraz wartość działającej asyptotycznie siły. Stałe reologiczne mazi stawowej oszacowano na podstawie danych eksperymentalnych.
7
Content available remote Mixed convection flow of micropolar fluid in a vertical channel with symmetric and asymmetric wall heating conditions
88%
Umavathi J. C. , Prathap Kumar J.
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tom Vol. 16, no 1
141-159
EN
The theory of micro polar fluids due to Eringen is used to formulate a set of equations for the mixed convective flow and heat transfer in a vertical channel. The two boundaries of the channel are kept either at equal or at different temperatures. Through a proper choice of non-dimensional variables and parameters, the governing equations are developed and three types of thermal boundary conditions are prescribed. These thermal boundaries are isothermal-isothermal, isoflux-isothermal and isothermal-isoflux for the left-right walls of the channel. Exact analytical solutions are obtained for the velocity and temperature fields for heat generation/absorption conditions. It is found that the material and source/sink parameters have significant effects on the flow. A parametric study is conducted and the results are presented and discussed. By making the Newtonian solvent more and more micropolar, it is possible to obtain drag reduction.
8
Content available remote On the peristaltic transport of a micropolar fluid
88%
Dey K. N. , Poria S. , Mazumdar H. P.
Engineering Transactions
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2005
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tom Vol. 53, iss. 1
3-14
EN
In this paper, we study some characteristics of the peristaltic motion of an incompressible micropolar fluid through a circular cylindrical tube. Many authors have investigated the peristaltic motion of non-Newtonian or viscoelastic fluid through a channel or tube due to the relevance of peristaltic action in both mechanical and physiological situations. For example, peristaltic mechanism may be involved in vasomotion of small blood vessels. Here the microstructural effects on the pressure rise, average flow and friction force are investigated.
9
Natural convection in a micropolar fluid with internal heat generation and viscous dissipation
88%
El-Hakiem M. A. , Gorla R. S. R.
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tom Vol. 4, no 4
789-799
EN
A similarity solution is presented for the flow of a micropolar fluid along an isothermal vertical plate with an exponentially decaying heat generation term and viscous dissipation. Numerical solutions are obtained for the governing equations. The data for friction factor, Nusselt number and wall couple stress have been tabulated for a range of Prandtl numbers and micropolar parameters.
10
Content available remote The flow of a micropolar fluid through a porous channel with expanding or contracting walls
88%
Si X. , Zheng L. , Zhang X. , Chao Y.
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nr 3
825-834
EN
The flow of a micropolar fluid in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using similar transformations. Homotopy analysis method (HAM) is employed to obtain the expressions for the velocity fields and microrotation fields. Graphs are sketched for the effects of some values of parameters, especially the expansion ratio, on the velocity and microrotation fields and associated dynamic characteristics are analyzed in detail.
11
Content available remote Steady axisymmetric flow and heat transfer of micropolar fluid over a vertical permeable slender cylinder in the presence of thermal radiation
75%
Mansour M. A. , Mohamed R. A. , Abd Elaziz M. M. , Ahmed S. E.
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tom Vol. 15, no 4
1185-1203
EN
The effects of thermal radiation and suction/blowing on an axisymmetric flow and heat transfer of a micropolar fluid over a vertical slender cylinder are analyzed. The partial differential equations governing the flow and heat transfer have been transformed to ordinary differential equations by using similarity transformations which are then solved numerically. The numerical results are validated by favorable comparisons with previously published results. The cases of buoyancy-assisted flow, pure mixed convection, buoyancy opposed flow, permeable cylinder, impermeable cylinder, Newtonian fluids and non-Newtonian fluids as well as the case which represents concentrated particle flow in which the microelements close to the wall surface are unable to rotate and the case which indicates vanishing of an antisymmetric part of the stress tensor are considered. A parametric study of the governing parameters, namely the buoyancy parameter, suction/injection parameter, radiation parameter, vortex viscosity parameter, curvature parameter and microgyration boundary conditions parameter on the linear velocity, angular velocity and temperature as well as the wall stress, wall couple stress and the rate of heat transfer is conducted. A selected set of numerical results is presented graphically and discussed.
12
Content available Unsteady natural convection in micropolar nanofluids
75%
Rup K. , Nering K.
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tom Vol. 35, no. 3
155--170
EN
This paper presents the analysis of momentum, angular momentum and heat transfer during unsteady natural convection in micropolar nanofluids. Selected nanofluids treated as single phase fluids contain small particles with diameter size 10-38.4 nm. In particular three water-based nanofluids were analyzed. Volume fraction of these solutions was 6%. The first of the analyzed nanofluids contained TiO2 nanoparticles, the second one contained Al2O3 nanoparticles, and the third one the Cu nanoparticles.
13
Content available remote Effect of homogeneous chemical reaction on solutal analog of Rayleigh-Benard convection in a micropolar fluid
75%
Siddheshwar P. G. , Desseaux A.
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tom Vol. 7, no 2
513-525
EN
The solutal analog of the Rayleigh-Benard convection in a reactive micropolar fluid is studied numerically using the Rayleigh-Ritz method. The solute concentration is assumed to disappear at a rate which is linearly proportional to the concentration. It is observed that the critical solutal Rayleigh number for this fluid system with homogeneous kinetics is greater than that of a non-reactive fluid system. The results have possible industrial applications.
14
Content available remote Hall and ion-slip effects on the flow of micropolar fluid between parallel plates
75%
Srinivasacharya D. , Shiferaw M.
International Journal of Applied Mechanics and Engineering
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2008
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tom Vol. 13, no 1
251-262
EN
The steady flow of an incompressible and electrically conducting micropolar fluid between two parallel infinite plates is studied taking Hall and ionic effects into consideration. The fluid motion is due to the constant pressure gradient. An extemal uniform magnetic field directed perpendicular to the flow direction is applied. The expressions for the velocity and micro rotation are obtained. The effects of micropolar parameters, magnetic parameter, Hall parameter and ion slip parameter on the velocity, and micro rotation are discussed.
15
Content available Micropolar flow over a black isothermal plate in the presence thermal radiation
75%
Raptis A.
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2021
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tom Vol. 26, no. 2
235--241
EN
This study numerically investigates the effects of thermal radiation on the flow over a black isothermal plate for an optically thin gray micropolar fluid. The flowing medium absorbs and emits radiation, but scattering is not included. The computational results are discussed graphically for several selected flow parameters.
16
Content available remote Thermal non-equilibrium model for mhd micropolar free convection from elliptic cylinders in a porous medium
75%
Mansour M. A. , Gorla R. S. R. , Abd El-Aziz M. M. , Ahmed S. E.
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tom Vol. 14, no 2
443-459
EN
This work uses a thermal non-equilibrium model to study the free convection boundary layer flow from cylinders of elliptic cross-section with uniform suction or injection in a micropolar fluid through a porous medium in the presence of a uniform magnetic field. The transformed conservation equations of the nonsimilar boundary layers are solved numerically by the shooting technique with a fourth-order Runge-Kutta integration scheme and the results compare very well with published results. The results obtained are displayed graphically to illustrate the influences of different physical parameters on the local heat transfer rate (Nusselt number) for the fluid and solid phases, velocity, angular velocity and streamlines.
17
Content available remote Effect of thermal stratification on MHD free convection flow of a micropolar fluid over a stretching surface
63%
Mahdy A.
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tom Vol. 16, no 3
763-773
EN
This paper analyses the flow and heat transfer characteristics of free convection in the boundary layer flow of a micropolar fluid past a stretching surface with magnetic field, thermal stratification, and heat generation or absorption effects. A similarity transformation was employed to change the governing momentum, angular momentum, and energy partial differential equations into ordinary ones. Then the numerical solution of the problem is derived using the Runge-Kutta Gill method. The sheet is linearly stretched in the presence of a uniform free stream of constant velocity. Numerical results are shown in a tabular form and graphically for the velocity, angular velocity, and temperature as well as the skin-friction and wall heat transfer rate and discussed for various physical parametric values.
18
Content available On axisymmetrical boundary problem of unsteady motion of micropolar fluid in the half-space
63%
El-Sirafy I. H. , Aboutahoun A. W.
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tom Vol. 64, nr 1
51--62
EN
The aim of this paper is developing an exact solution for the problem of axisymmetrical flow of unsteady motion of micropolar fluid in the half-space when the shear stresses are given on the boundary. The Laplace-Hankel transform technique is used to solve this problem. Some physical quantities such as velocities, pressure and microrotations are obtained and illustrated numerically.
19
Content available Analytical solution to the MHD flow of micropolar fluid over a linear stretching sheet
63%
Siddheshwar P. G.
International Journal of Applied Mechanics and Engineering
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2015
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tom Vol. 20, no. 2
397--406
EN
The flow due to a linear tretching sheet in a fluid with suspended particles, modeled as a micropolar fluid, is considered. All reported works on the problem use numerical methods of solution or a regular perturbation technique. An analytical solution is presented in the paper for the coupled non-linear differential equations with inhomogeneous boundary conditions.
20
Content available Unsteady MHD mixed convection flow of a micropolar fluid over a vertical wedge
63%
Roy N. C. , Gorla R. S. R.
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tom Vol. 22, no. 2
363--391
EN
An analysis is presented to investigate the unsteady magnetohydrodynamic (MHD) mixed convection boundary-layer flow of a micropolar fluid over a vertical wedge in the presence of thermal radiation and heat generation or absorption. The free-stream velocity and surface temperature are assumed to be oscillating in magnitude but not in the direction of the oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the finite difference method for the entire frequency range, and the series solution for low frequency range and the asymptotic series expansion method for the high frequency range. Numerical solutions provide a good agreement with the series solutions. The amplitudes of skin friction and couple stress coefficients are found to be strongly dependent on the Richardson number and the vortex viscosity parameter. The Prandtl number, the conduction-radiation parameter, the surface temperature parameter and the pressure gradient parameter significantly affect the amplitudes of skin friction, couple stress and surface heat transfer rates. However, the amplitudes of skin friction coefficient are considerably affected by the magnetic field parameter, whereas the amplitudes of heat transfer rate are appreciably changed with the heat generation or absorption parameter. In addition, results are presented for the transient skin friction, couple stress and heat transfer rate with the variations of the Richardson number, the vortex viscosity parameter, the pressure gradient parameter and the magnetic field parameter.
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