Double diffusion, natural convection in an enclosure filled with saturated porous medium subjected to cross gradients; stably stratified fluid

Two- and three-dimensional flows, heat and mass transfer in a horizontal enclosure with aspect ratio of two filled with saturated porous medium were analyzed numerically. The enclosure is heated differentially and stably stratified species concentration is imposed vertically. The Prandtl number is fixed to 10 (aqueous solutions). The Lewis number is varied in the range of 1.0–1000 to cover a wide range of species diffusion material in water. The work is concentrated on stable stratified flow. The results of two- and three-dimensional models were compared. Interesting results are obtained for a wide range of solutal to thermal buoyancy ratios. The difference in the rate of heat and mass transfer between prediction of three- and two-dimensional simulations is not that significant, even though the flow exhibits a three-dimensional structure. This is due to the fact that the spanwise flow is very weak when compared with main flow.