Effect of alternating gradient magnetic field on heat transfer enhancement of magnetoreological fluid flowing through microchannel

Abstract

To investigate the contribution of transverse velocity pulsation on the heat transfer enhancement of magnetoreological fluid (MRF) flow in microchannel subjected to gradient alternating magnetic field, a doubled-population lattice Boltzmann simulation method is developed, where the magnetic nanoparticles (MPs) are treated as a quasi fluid and a simplified evaluation method for external forces on solid phase lattice points is proposed. Primarily, the effects of the alternating gradient magnetic field on the velocity and temperature distributions under temperature and heat flux boundary conditions are investigated. Simulation results show that, affected by the alternating gradient magnetic field, a considerable transverse velocity component occurs in the flow field. With the increase of pressure difference, the Nusselt number increases while the mean temperature of MRF reduces. The Nusselt number changes fluctuantly when the gradient magnetic field alternates. For the model concerned in this work, the gradient magnetic field induced transverse motion of fluid particles do not affect the heat transfer enhancement significantly. The experimental results indicate that both the heat transfer coefficient and the Nusselt number increase with the increasing Reynolds number, and the increasing magnetic induction intensity results in an obvious increase of heat transfer effect.