Thermally driven cavity flows in porous media II. The horizontal boundary layer structure

Abstract

An analysis is given of the structure, at high Rayleigh numbers, of thermally driven cavity flows in fluid-saturated porous media. Particular emphasis is placed on the description of the diffusive layers near the horizontal surfaces. Solutions consistent with the core behaviour determined in part I of this series are obtained. These solutions, which are new, indicate that the horizontal boundary layers have a double structure in which the outer layer has a thickness O ( R -¼ ), where R is the Rayleigh number. Corner interactions between the horizontal and the vertical boundary layers are also discussed, and the present theory provides a first-order description of the entire flow field.