Regularized lattice Boltzmann model for double-diffusive convection in vertical enclosures with heating and salting from below

Abstract

Double-diffusive convection in enclosures with vertical temperature and concentration gradients is an important problem in both science and engineering. In this paper, we first present a regularized lattice Boltzmann model for temperature field or concentration field, and then validate the present model through numerical simulations of two-dimensional (2D) Rayleigh-Bénard convection in a square cavity. Finally, the proposed model is used to study double-diffusive convection in vertical enclosures with aspect ratio (i.e., A=H/L with H and L being the enclosure depth and width) equaling 2.0 and 4.0. To improve the computational efficiency, all simulations are performed on the Graphics Processing Unit (GPU) using NVIDIA’s CUDA. The results show that the vortex number of flow field, recirculation zones of isotherms and iso-concentrations increase in aspect ratio. And additionally, the average Nusselt and Sherwood numbers almost keep constant during the conduction and diffusion dominated stage, and then increase with the increase of Rayleigh number or buoyancy ratio during the convection dominated stage. Moreover, it is also found that the heat and mass transfer rates are decreased with the increase of the aspect ratio.