Lattice Boltzmann simulation of nanofluid conjugate heat transfer in a wide microchannel: effect of temperature jump, axial conduction and viscous dissipation

Abstract

In the present study, conjugate heat transfer of nanofluid in a wide microchannel with thick wall, by considering the velocity slip and temperature jump on the fluid–solid interface and also the effect of viscous dissipation is investigated. For numerical solution of velocity field, preconditioned lattice Boltzmann method (PLBM) based on standard LBM, and for temperature field, standard LBM are used. Upper wall of the microchannel is insulated and uniform heat flux is imposed on the lower wall of the solid region. For applying the temperature jump boundary condition on the fluid–solid interface, a new algorithm reported here, is used. The problem is solved for dimensionless slip coefficient 0–0.1, volume fraction 0, 0.02 and 0.04, nanoparticles diameters (10–50) nm, and also Reynolds numbers 10–150. The results of the presented algorithm for conjugate heat transfer with temperature jump at the fluid–solid interface, show good agreement with analytical and other numerical solutions. Also, it is shown that in conjugate heat transfer of nanofluid, using super hydrophobic surfaces not only has no considerable negative effect on the average Nusselt number, but also it can increase it, especially in higher Reynolds numbers. As well as, in conjugate heat transfer, unlike the conditions of ignoring the wall thickness (at constant heat flux boundary condition), temperature jump on the wall is not constant and depends on the Reynolds number. On the other hands, using super hydrophobic surfaces (considering velocity slip and temperature jump on the wall), decreases the effect of viscous dissipation, specially at higher volume fraction of nanoparticles.