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1
Content available MHD flow and heat transfer of a micropolar fluid over a stretchable disk
Ashraf M., Batool K.
Journal of Theoretical and Applied Mechanics
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2013
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Vol. 51 nr 1
25--38
EN
A numerical study of an axisymmetric steady laminar incompressible flow of an electrically conducting micropolar fluid over a stretchable disk is carried out when the fluid is subjected to an external transverse magnetic field. The governing nonlinear equations of motion are transformed into a dimensionless form through Von Karman’s logic similarity functions. An algorithm based on a finite difference scheme is used to solve the reduced coupled nonlinear ordinary differential equations with the associated boundary conditions. Effects of the micropolar parameters, the magnetic parameter and the Prandtl number on the flow velocity and temperature distribution are discussed. Investigations predict that the heat transfer rate at the surface of the disk increases with an increase in the values of micropolar parameters. The magnetic field enhances the shear and couple stresses. The shear stress factor is lower for micropolar fluids as compared to Newtonian fluids, which may be beneficial in flow and heat control of polymeric processing.
PL
W pracy zaprezentowano wyniki badań numerycznych nad osiowo-symetrycznym, laminarnym i ustalonym opływem elektrycznie przewodzącej cieczy mikropolarnej wokół rozciągliwego dysku przy jednoczesnym oświetleniu cieczy polem magnetycznym. Nieliniowe równanie ruchu opływu sprowadzono do postaci bezwymiarowej za pomocą funkcji podobieństwa von Karmana. Do rozwiązania uproszczonych, sprzężonych i nieliniowych równań różniczkowych zwyczajnych z towarzyszącymi warunkami brzegowymi użyto algorytmu opartego na metodzie różnic skończonych. Przedyskutowano wpływ parametrów mikropolarności, wartości pola magnetycznego oraz liczby Prandtla na rozkład prędkości i temperatury cieczy. Według badań, tempo przepływu ciepła na powierzchni dysku wzrasta z rosnącymi wartościami parametrów mikropolarności. Dodatkowo, obecność pola magnetycznego powiększa naprężenia ścinające i momentowe. Wartość naprężeń ścinających jest mimo to mniejsza dla cieczy mikropolarnej niż dla newtonowskiej, co może być korzystne w monitorowaniu przepływu i transferu ciepła podczas procesu obróbki polimerów.
2
Content available remote The effect of variable viscosity on MHD natural convection in micropolar fluids
El-Hakiem M. A., Modather M., Abdou M.
International Journal of Applied Mechanics and Engineering
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2006
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Vol. 11, no 2
301-320
EN
The influence of variable viscosity and a transverse magnetic field on natural convection in micropolar fluids is examined. The fluid viscosity is assumed to vary as an inverse linear function of temperature. Four different vertical flows have been analyzed, those adjacent to an isothermal surface and uniform heat flux surface, a plane plume and flow generated from a horizontal line energy source on a vertical adiabatic surface, or wall plume. By means of similarity solutions and deviation of the velocity, temperature and micro-rotation fields as well as the skin friction, heat transfer and wall couple stress results from their constant values are determined.
3
Content available remote Effect of heat and mass transfer on free convection flow over a cone with uniform suction or injection in micropolar fluids
El-Kabeir S. M., Modather M., Mansour M. A.
International Journal of Applied Mechanics and Engineering
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2006
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Vol. 11, no 1
15-35
EN
A regular perturbation is presented to study the effect of heat and mass transfer on free convection flow with a uniform suction and injection over a cone in a micropolar fluid. The velocity, temperature, concentration and microrotation profiles were computed for various values of suction/injection, Schmidt number and micropolar parameters. The governing equations are first cast into a dimensionless form by a nonsimilar transformation and the resulting equations are then solved numerically by using the Runge-Kutta numerical integration, the procedure in conjunction with the shooting technique. The results indicate that as the micropolar parameter increases the wall couple stress, the shear stress, the Nusselt number and Sherwood number decrease with it. While the Shmidt number increases the shear stress, the wall couple stress and Nusselt number decrease, the opposite is true for the Sherwood number. The results are shown in figures and tables followed by a quantitative discussion.
4
Content available remote Convective micropolar boundary layer flows over a wedge with constant surface heat flux
Kim Y. J., Kim T. A.
International Journal of Applied Mechanics and Engineering
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2003
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Vol. 8, no spec.
147-153
EN
In this study, the steady laminar boundary layer flow of micropolar fluids over a wedge has been examined with the constant heat flux boundary condition on the wedge surface. The similarity variables found by Falkner and Skan are employed to reduce the streamwise-dependence in the coupled nonlinear boundary layer equations. Numerical solutions are presented for the heat transfer characteristics using the fourth-order Runge-Kutta numerical procedure with shooting method. The micro-rotation velocity and temperature distributions across the boundary layer are plotted with different wedge angles and compared with the corresponding flow problems for a Newtonian fluid.
5
Content available remote On thermal convection in micropolar fluids in presence of suspended particles
Mohan H., Kumar P., Anjula
Studia Geotechnica et Mechanica
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2002
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Vol. 24, nr 3-4
53--63
PL
Opisano niestabilność termiczną płynów mikropolamych w obecności cząstek zawieszonych. Sprzężenie między ruchem wirowym a strumieniami ciepła może być przyczyną nadstabilnych stanów w układzie. Zawieszone cząstki wprowadzają także drgania w układzie, a wartość liczby Rayleigha zmniejsza się ze zwiększeniem liczby cząstek zawieszonych.
EN
The thermal instability of micropolar fluids in the presence of suspended particles has been considered. The coupling between spin and heat fluxes may bring overstable modes in the system. The suspended particles also introduce oscillatory modes in the system and the Rayleigh number is found to decrease with the increase in suspended particles.
6
Content available remote Combined thermal and diffusion buoyancy effects in micropolar fluids
Mansour M. A., Mohammadein A. A., El Kabeir S. M., Gorla R. S. R.
International Journal of Applied Mechanics and Engineering
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2001
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Vol. 6, no 2
551-572
EN
A regular perturbation analysis is presented for the laminar natural convection flows of micropolar fluids with temperature dependent viscosity: a freely-rising plane plume, the flow above a horizontal line source on an adiabatic surface (a plan wall plume) and the flow adjacent to a vertical uniform flux surface. While these flows have well-known power-law similarity solutions when the fluid viscosity is taken to be constant, they are non-similar when the viscosity is considered to be a function of temperature. A flow adjacent to a vertical isothermal surface is also analyzed for comparison in order to estimate the extent of validity of the perturbation analysis. The formulation used here provides a unified treatment of variable viscosity effects on those four flows. Computed first-order perturbation quantities are presented for all four flows. The velocity, microrotation distribution, temperature and concentration profiles are shown. Numerical results are presented for the local Nusselt number and Sherwood number, wall shear stress and wall couple stress.
7
Content available remote Analiza przepływu w mikroszczelinie na gruncie teorii płynów mikropolamych
Kucaba-Piętal A., Migoun N.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2000
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nr 117, vol. 1
47-52
PL
W pracy przedstawiono wyniki numeryczne dotyczące przepływu płynu mikropolamego w wąskiej szczelinie między równoległymi płytkami, gdy jedna z nich zbliża się do drugiej (squeezing flow). Dzięki uzyskanej analitycznej postaci rozwiązania [3] przeprowadzono analizę wpływu wartości wektora mikrorotacji na ściankach na wielkości hydrodynamiczne i trybologiczne (nośność, czas zbliżenia) charakteryzujące przepływ w łożysku. Niezbędne obliczenia uzyskano za pomocą programu Mathcad 7.
EN
In the present paper we study the narrow squeeze film of micropolar fluid between two plates. Thanks the analytical solution obtained [3] we examine the effects of non-zero values of microrotation vector on the walls on hydrodynamic and tribological characteristics of the flow.
8
Micropolar fluid flow past a continuously moving plate in the presence of magnetic field
Mansour M. A., Gorla R. S. R.
Applied Mechanics and Engineering
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1999
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Vol. 4, no 4
663-672
EN
A similarity analysis of the flow and heat transfer with magnetic field past a continuously moving semi-infinite permeable plate in a micropolar fluid is presented. The velocity, micro-rotation distribution, the temperature profiles, the skin friction and the rate of heat transfer are shown on graphs. Also the numerical values of the skin friction and the rate heat transfer are entered in tabular form.
9
MHD mixed convection boundary layer flow of a micropolar fluid from A horizontal cylinder
Mansour M. A., Gorla R. S. R.
Applied Mechanics and Engineering
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1999
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Vol. 4, no 4
649-662
EN
A boundary layer solution is presented to study the mixed convection from a horizontal cylinder embedded in electrically conducting micropolar fluid. The governing conservation equations have been solved numerically. Details of the velocity, microrotation and temperature fields are presented for various material parameters. Missing values of the velocity, angular velocity and thermal functions are tabulated.
10
Effect of a transverse magnetic field on natural convection boundary layer flow of a micropolar fluids in a porous medium
El-Hakiem M. A.
Applied Mechanics and Engineering
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1999
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Vol. 4, no 3
509-528
EN
A boundary layer analysis is presented to study the effects of a transverse magnetic field on natural boundary layer flow of a micropolar fluid in a porous medium. Four different vertical flows have been analyzed, those adjacent to an isothermal surface and uniform heat flux surface, a plane plume and flow generated from a horizontal line energy source on a vertical adiabatic surface, or wall plume. The governing equations for momentum, angular momentum and energy have been solved numerically. Missing values of the velocity, angular velocity and thermal functions are tabulated for a wide range of the material parameters, Prandtl number and magnetic parameter of the fluid. A comparison has been made with the corresponding results for Newtonian fluids. Micropolar fluids display drag reduction and reduced surface heat transfer rate in a porous medium as compared with Newtonian fluids.
11
Variable viscosity effects on natural convection in micropolar fluid at an axisymetric stagnation point
Mohammadein A. A., El-Kabeir S. M., Gorla R. S. R.
Applied Mechanics and Engineering
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1998
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Vol. 3, no 4
539-552
EN
A three-dimensional boundary layer solution is presented for the natural convection in a micropolar fluid in the vicinity of an axisymmetric stagnation point on heated vertical surfaces. The effects of variable viscosity are included. The governing equations for the velocity, microrotation and temperature fields are solved numerically.
12
Effects of a transverse magnetic field on natural convection with temperature dependent viscosity in micropolar fluids
El-Hakiem M.
Applied Mechanics and Engineering
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1998
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Vol. 3, no 2
287-304
EN
A regular parameter perturbation analysis is presented to study the effect of uniform transverse magnetic field with temperature dependent viscosity in micropolar fluids. Four different vertical flows have been analyzed: these adjacent to an isothermal surface, uniform heat flux surface, a plane plume and wall plume. Viscous dissipation, motion pressure and volumetric energy source effects are neglected. The absolute viscosity 'mi' is taken to be variable in the force momentum balance while the fluid volumetric coefficient of thermal expansion, 'beta', specific heat, Cp and thermal conductivity, k, are assumed to be constant. Numerical solutions are obtained for different values of the magnetic field, material parameters and micropolar parameters.
13
Boundary layer heat transfer in a micropolar fluid over a flat plate with vectored surface mass transfer
Hassanien I. A., Gorla R. S. R., Mohammadein A. A.
Applied Mechanics and Engineering
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1998
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Vol. 3, no 1
25-37
EN
An analysis is presented for the heat transfer in a micropolar fluid boundary layer over a flat plate with uniformly distributed vectored surface mass transfer. Numerical solutions for the governing nonsimilar boundary layer equations are presented for a range of values of the material properties and Prandtl number of the fluid. The results indicate that the micropolar fluids display a reduction in drag as well as heat transfer rate when compared with Newtonian fluids.
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