Combined double-diffusive convection and radiation in a square enclosure filled with semitransparent fluid
A 2D numerical assessment of coupled double diffusive convection and volumetric radiation in a differentially heated square enclosure filled with a gray fluid participating in absorption, emission and non-scattering is carried out. Temperatures and concentrations are imposed at the vertical walls, whereas the horizontal walls are insulated and impermeable. All cavity walls are assumed to be opaque, diffuse and gray. The governing equations are solved by a hybrid scheme with multiple relaxation time lattice Boltzmann (MRT-LBM) and finite difference method (FDM). The velocity field is computed by D2Q9 MRT model while the temperature field is determined by resolution of the energy equation using FDM. The radiative source term in the energy equation is calculated by the discrete ordinates method (DOM) with 58 quadrature. A parametric study illustrating the influence of the buoyancy number (N) and the wall emissivity (epsilon(i)) on the flow field and the heat and mass transfer is performed. Results are presented in terms of isotherms, streamlines, iso-concentrations, Nusselt and Sherwood numbers. Generally the isotherms and iso-concentrations are inclined in the core cavity, the flow is more stabilized in presence of cooperating flow case but opposing flows are found to be a catalyser of the multi-cellular structures. (C) 2012 Elsevier Ltd. All rights reserved.
volumetric radiation discrete ordinate method numerical analysis heat transfer double diffusive natural convection lattice boltzmann method