Three-dimensional analysis of magnetohydrodynamic transverse mixed convection of nanofluid inside a lid-driven enclosure using MRT-LBM

Abstract

In the current study, an in-house parallel multi-relaxation time lattice Boltzmann method (MRT-LBM) code is developed to resolve and investigate the mixed convection magneto-hydrodynamic (MHD) Cu-water nanofluid flow inside a three-dimensional enclosure with lid-driven walls. The lid-driven walls are moving in different directions with various velocities to form 3D mixed convection (including natural caused by temperature difference and forced convection effects) with a complex mixing within the enclosure. In addition, the magnetic body force effects on the 3D mixed convection flow are observed in terms of the heat transfer and flow characteristics. Accordingly, the complex mixing of flow and heat transfer due to natural convection, moving wall and magnetic field effects is investigated in 3D. In order to scrutinize these three forces effects on the flow characteristics and heat transfer, results are presented and analyzed for various moving wall directions, nanoparticle concentrations (0, 0.2, 0.4, 0.6), Richardson numbers (0.5, 1, 5), Rayleigh numbers (103, 104, 105) and Hartmann numbers (20, 40). It has been shown that the transverse and opposed mixed convection modes have significant negative impacts on the heat transfer. While, the concurrent mixed convection mode remarkably improves the heat transfer. Moreover, the 3D mixing of the transverse mixed convection mode is better than the other cases. Also, though the magnetic field has an undesirable impact on Nusselt, especially in high Ha numbers, but, aligning the MHD force direction and the natural convection circulation plane alleviates this negative impact and makes it ignorable. A comprehensive comparison is made between different cases, and in some situations 30% reduction in heat transfer is observed in comparison with the best case.