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Mixed convective flow of unsteady hydromagnetic couple stress fluid through a vertical channel filled with porous medium

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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.

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MHD mixed convection in copper-water nanofluid filled lid-driven square cavity containing multiple adiabatic obstacles with discrete heating

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Gorla R. S. R. , Siddiqa S. , Hasan A. A. , Salah T. , Rashad A. M.

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tom Vol. 25, no. 2

57--74

EN

The objective of the present work is to investigate the influence of nanoparticles of copper within the base fluid (water) on magneto-hydrodynamic mixed-convection flow in a square cavity with internal generation. A control finite volume method and SIMPLER algorithm are used in the numerical calculations. The geometry is a lid-driven square cavity with four interior square adiabatic obstacles. A uniform heat source is located in a part of the left wall and a part of the right wall of the enclosure is maintained at cooler temperature while the remaining parts of the two walls are thermally insulated. Both the upper and bottom walls of the cavity are considered to be adiabatic. A comparison with previously published works shows a very good agreement. It is observed that the Richardson number, Ri, significantly alters the behavior of streamlines when increased from 0.1 to 100.0. Also, the heat source position parameter, D, significantly changes the pattern of isotherms and its strength shifted when D moves from 0.3 to 0.7.

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84%

Ibrahim F. S. , Omer G. M.

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tom Vol. 5, nr 2

155-168

EN

The problem of mixed convection along non-isothermal vertical flat plate embedded in a porous medium with variable permeability is analyzed. Non-similar solutions are obtained for power- law variation of the surface heat flux in the form qw(x) = bxm. The entire mixed convection regime is covered by non-similarity parameter ζ = [1+Rax/Pe3/2x)1/3]-1, from pure forced convection ζ = 1 to pure free convection ζ = 0.0. A finite difference scheme was used to solve the system of transformed governing equations. Velocity and temperature profiles, and local Nusselt numbers are presented. It is found that as ζ decreases from 1 to 0, the thermal boundary thickness increases first and then decreases. But the local Nusselt number in the form Nux(Pe1/2x+Ra1/3x)-1 decreases first and then increases. The variation of permeability increases Nusselt number of all values of ζ.

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Buoyancy and Soret effect on unsteady MHD mixed convective slip flow in a permeable vertical plate

84%

Rashi Kumar B. , Sivaraj R.

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2012

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tom Vol. 17, no. 1

179-190

EN

This paper is focused on the study of heat and mass transfer in the unsteady MHD mixed convective flow of a viscous incompressible fluid bounded by a permeable vertical plate subject to the influence of buoyancy, viscous dissipation, ohmic heating and the Soret effect embedded with slip condition at the boundary layer. In order to obtain a better insight into this problem, we make use of the perturbation method. The results for velocity, temperature, concentration, skin friction, the Nusselt number as well as the Sherwood number are examined analytically and the effects of various significant parameters entering into this problem are displayed graphically.

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Mixed radiation-convection boundary layer flow of an opically dense fluid along a vertical flat plate in a non-Darcy porous medium

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Takhar H. S. , Beg O. A. , Chamkha A. J. , Filip D. , Pop I.

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2003

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tom Vol. 8, no 3

483-496

EN

The combined effects of thermal radiation flux, thermal conductivity, Reynolds number and non-Darcian (Forcheimmer drag and Brinkman boundary resistance) body forces on steady laminar boundary layer flow along a vertical surface in an idealized geological porous medium are investigated. The classical Rosseland one-dimensional diffusion approximation is implemented in the energy equation to avoid solving the general integro-differential equation for radiative transfer. Pseudo-similarity transformations are invoked and the resulting highly coupled and non-linear set of ordinary differential equations for momentum and energy equations are solved numerically using a well-tested and highly accurate shooting Runge-Kutta quadrature with a Merson-Gill algorithm. It is shown that the dimensionless velocity functions generally increase with rising radiation parameter and the Prandtl number, and the dimensionless temperature functions decrease as the non-Darcian body forces decrease. It is also shown that the dimensionless temperature functions rise in magnitude with rising radiation parameter and the Prandtl number but are depressed by lowered non-Darcian resistance parameter and rising Reynolds number. Generally radiation is seen to substantially boost the overall heat transfer.

6

Mixed convective flow with variable viscosity and variable thermal conductivity in a channel in the presence of first order chemical reaction with heat generation or absorption

84%

Shobha K. C. , Biradar M. , Mallikarjun B P.

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2021

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tom Vol. 20, nr 1

91--102

EN

A study has been made on the flow and heat transfer of a viscous fluid in a vertical channel with first order chemical reaction and heat generation or absorption assuming that the viscosity and thermal conductivity are dependent on the fluid temperature. The temperature of the walls is maintained constant. Under these assumptions, the governing balance equations of mass, momentum and energy are formulated. The dimensionless forms of the governing equations are coupled and non-linear, which cannot be solved analytically and therefore require the use of the Runge-Kutta fourth order along with shooting technique. Graphs for velocity and temperature under different values of parameters involved are plotted and discussed. The skin friction and Nusselt number on the channel walls are also computed and discussed. Furthermore, the investigation found that variable viscosity and variable thermal conductivity enhance the velocity and temperature of the flow.