Magnetic field effects on nanoparticle migration and heat transfer of alumina/water nanofluid in a parallel-plate channel with asymmetric heating
Department of Mechanical Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur, Iran
2 Mechanical Engineering Department, Babol University of Technology, Babol, Iran
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Accepted: 12 March 2015
Published online: 7 April 2015
The present paper is a theoretical investigation on the effects of nanoparticle migration and asymmetric heating on magnetohydrodynamic forced convection of alumina/water nanofluid in a parallel-plate channel. Walls are subjected to different heat flux; q″ t for the top wall and q″ b for the bottom wall, such that q″ t > q″ b . A two-component mixture model is used for the nanofluid in the hypothesis that Brownian motion and thermophoretic diffusivities are the only significant slip mechanisms between solid and liquid phases. Considering the hydrodynamically and thermally fully developed flow, governing equations including continuity, momentum, and energy equations have been reduced to ordinary differential equations and solved numerically. It is revealed that nanoparticles eject from the heated walls, construct a depleted region, and accumulate in the core region, but are more likely to take place toward the wall with the lower heat flux. Also, the non-uniform nanoparticle distribution makes the velocities move toward the wall with the higher heat flux and enhances the heat transfer rate there. In addition, it is shown that the advantage of nanoparticle inclusion is increased in the presence of a magnetic field, though heat transfer enhancement is decreased.
© Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg, 2015