On the Thermal Instability of Superposed Porous and Fluid Layers

Abstract

A solution is presented for the problem of predicting the onset of convection for a system consisting of a volumetrically heated porous bed saturated with and overlaid with a fluid, heated or cooled from below. Results are presented in graphical form in terms of the external Rayleigh number based on the fluid layer, which is shown to be the sole stability parameter of the problem. A wide range of independent parameters are investigated and physical justification for the behavior of the instability with respect to them is given. Finally, the results are compared with the two bounding cases of the problem and are found to be in agreement with them.