Effects of interaction between Rayleigh and Marangoni convection in superposed fluid and porous layers

Abstract

This paper is aimed at investigating the effects of combined Marangoni and Rayleigh convections in a liquid layer, underlain by a porous layer. The two-dimensional numerical model consists of a dual rectangular cavity system in which the porous cavity is located below the fluid cavity. Both cavities are saturated with the same liquid. The interaction between the Marangoni and the Rayleigh convection is investigated in detail. The porous cavity is heated at the bottom while the top liquid cavity has a free surface and heat is lost to the environment by natural convection. The role of the ratio of the liquid layer over the porous layer in determining the convection pattern was studied. Results indicate that the Marangoni convection enhances the flow in the liquid layer, which results in a reduction of the buoyancy convection in the porous layer. A large heat transfer across the liquid layer was noticeable by displaying the variation of the Nusselt number with the liquid Rayleigh number.