Effects of radiation and magnetic field on mixed convection stagnation-point flow over a cylinder in a porous medium under local thermal non-equilibrium

Alizadeh, R., Karimi, N. and Nourbakhsh, A. (2020) Effects of radiation and magnetic field on mixed convection stagnation-point flow over a cylinder in a porous medium under local thermal non-equilibrium. Journal of Thermal Analysis and Calorimetry, 140, pp. 1371-1391. (doi: 10.1007/s10973-019-08415-1)

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Heat transfer enhancement and entropy generation are investigated in a nanofluid, stagnation-point flow over a cylinder embedded in a porous medium. The external surface of cylinder includes non-uniform transpiration. A semi-similarity technique is employed to numerically solve the three-dimensional momentum equations and two-equation model of transport of thermal energy for the flow and heat transfer in porous media. The mathematical model considers nonlinear thermal radiation, magnetohydrodynamics, mixed convection and local thermal non-equilibrium in the porous medium. The nanofluid and porous solid temperature fields as well as those of Bejan number are visualised, and the values of circumferentially averaged Nusselt number are reported. The results show that thermal radiation significantly influences the temperature fields and hence affects Nusselt and Bejan number. In general, more radiative systems feature higher Nusselt numbers and less thermal irreversibilities. It is also shown that changes in the numerical value of Biot number can considerably modify the predicted value of Nusselt number and that the local thermal equilibrium modelling may significantly underpredict the Nusselt number. Magnetic forces, however, are shown to impart modest effects upon heat transfer rates. Yet, they can significantly augment frictional irreversibility and therefore reduce the value of Bejan number. It is noted that the current work is the first systematic analysis of a stagnation-point flow in curved configurations with the inclusion of nonlinear thermal radiation and local thermal non-equilibrium.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Karimi, Dr Nader
Authors: Alizadeh, R., Karimi, N., and Nourbakhsh, A.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Journal of Thermal Analysis and Calorimetry
ISSN (Online):1572-8943
Published Online:03 June 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Journal of Thermal Analysis and Calorimetry 140:1371–1391
Publisher Policy:Reproduced under a Creative Commons License

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