Lattice Boltzmann simulation of MHD natural convection in a nanofluid-filled enclosure with non-uniform heating on both side walls

This paper examines the natural convection in a square enclosure filled with a water-Al2O3 nanofluid and is subjected to a magnetic field. The side walls of the cavity have spatially varying sinusoidal temperature distributions. The horizontal walls are adiabatic. Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature fields. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number of the base fluid, Ra=10(3) to 10(5), Hartmann number varied from Ha=0 to 90, phase deviation (gamma=0, pi/4, pi/2, 3 pi/4 and pi) and the solid volume fraction of the nanoparticles between phi=0 and 6%. The results show that the heat transfer rate increases with an increase of the Rayleigh number but it decreases with an increase of the Hartmann number. For gamma=pi/2 and Ra=10(5) the magnetic field augments the effect of nanoparticles. At Ha=0, the greatest effects of nanoparticles are obtained at gamma = 0 and pi/4 for Ra=10(4) and 10(5) respectively.