Double Diffusive Natural Convection in a Composite Fluid-Porous Layer

This study deals with natural convection driven by combined thermal and solutal buoyancy forces in a binary fluid. The consequence of thermosolutal convection on heat and mass transfer is examined in a confined enclosure partially filled with a porous medium. The mathematical description of the problem makes use of a one-domain formulation of the conservation equations. The presented numerical results quantitatively show the significant influence of the presence of a relatively thin porous layer on the flow structure and on heat and species transfer in the enclosure. The paper is dedicated to the analysis of the influence of the thickness and permeability of the porous layer in a range of governing parameters. For a low permeability porous layer, the numerical results are compared to an analysis based on simple scaling laws, which provide a good interpretation in terms of the wall transfer decrease with the porous layer thickness. The effect of permeability is investigated and it is shown that flow penetration in the porous layer induces a specific behavior of the flow structure and average heat transfer in the enclosure.