Natural convection in rectangular layers porous cavities

A numerical study was performed to further investigate the flow and temperature fields in layered porous cavity. The cavities considered have an aspect ratio of either 0.2 (shallow cavities) or 5 (tall cavities) with two or four sublayers. Similar to the case of square cavities, convection is always initiated in the more permeable sublayer. As the base Rayleigh number increases, the strength of the convective cell increases and leads to flow penetration to the less permeable sublayer. The results obtained were used to evaluate the validity of the boundary-layer assumption employed by other investigators. In addition, they were used to examine the feasibility of extending the lumped-system analysis from square cavities to rectangular ones. The averaging schemes in defining the effective permeability, as suggested in the previous study for a square cavity, were tested.