NATURAL-CONVECTION HEAT-TRANSFER FROM AN ISOTHERMAL VERTICAL SURFACE TO A FLUID-SATURATED THERMALLY STRATIFIED POROUS-MEDIUM

Presented here are the results of a numerical study of natural convect ion heat transfer in a stably stratified, fluid saturated low porosity medium, in which Darcy flow prevails. In this investigation, the boun dary layer approximations are discarded and a wide range of ambient th ermal stratification levels is considered. The results indicate that t he ambient thermal stratification has a significant effect on the flow and temperature fields, and that this effect differs considerably at higher levels of stratification. The flow reversal and temperature def ects are significantly smaller in the porous media than in a viscous f luid, due to the stabilization of the flow by the solid matrix. To gen eralize the result, the Nusselt number data are correlated with the th ermal stratification parameter to yield a functional relationship. (C) 1997 Elsevier Science Ltd.