Natural convection with combined heat and mass transfer buoyancy effects in a porous medium

This paper describes a comprehensive study of the natural convection phenomenon occurring inside a porous layer with both heat and mass transfer from the side. The natural circulation is driven by a combination of buoyancy effects due to both temperature and concentration variations. The first part of the study consists of an extensive series of numerical simulations conducted in the range 0.01 ⩽ Le ⩽ 100, 50 ⩽ Ra H ⩽ 104, − 5 ⩽ N ⩽ +3 and H/L = 1, where Le, Ra H , N and H/L are the Lewis number, Dareymodified Rayleigh number, buoyancy ratio and geometric aspect ratio of the porous layer. In the second part, the phenomenon is studied based on scale analysis : the chief conclusions of this part, namely, the order-ofmagnitude predictions for the overall heat and mass transfer rates and their respective domains of validity, are shown to be in agreement with the results produced by discrete numerical experiments. Furthermore, the scale analysis is used to sort out the many effects that influence the overall heat and mass transfer results of numerical experiments.