Investigation of Double Diffusive Natural Convection in Presence of Gray Gas Radiation Within a Square Cavity Using Multiple Relaxation Time Lattice Boltzmann Method

The present work proposes a coupling between the hybrid lattice Boltzmann, the finite difference method, and the discrete ordinates method to simulate combined double diffusive convection and volumetric radiation in a square cavity filled with an emitting and absorbing gray gas. The vertical walls are kept at different temperatures and pollutant concentrations, while the horizontal walls are insulated and impermeable. A parametric study is carried out to evaluate the influence of control parameters such as the Lewis number (Le), Planck number (Pl), and reference temperature ratio (Θ₀) on the flow field as well as on heat and mass transfer. The results are presented in terms of isotherms, streamlines, isoconcentrations, average Nusselt, and Sherwood numbers. They show that the volumetric radiation accelerates the flow and significantly alters the structure of the dynamic, concentration, and temperature fields, especially when the thermal forces are dominant. On the other hand, when the mass forces are dominant, the flow is slowed down. The influence of radiation is greater on the thermal field than on the dynamic and concentration fields.