• STABILITY OF POROUS MEDIUM CONVECTION IN POLARIZED DIELECTRIC FLUIDS WITH NON-CLASSICAL HEAT CONDUCTION

Abstract

The effect of second sound on the onset of Rayleigh-Bénard instability in a dielectric liquid saturated porous medium subject to the simultaneous action of a vertical ac electric field and a vertical temperature gradient is investigated theoretically by means of the method of small perturbations. Modified Darcy law is used to describe the fluid motion. The horizontal porous layer is cooled form the upper boundary, while an isothermal boundary condition is imposed at the lower boundary. The non-classical Maxwell-Cattaneo heat flux law involves a wave type heat transport and does not suffer from the physically unacceptable drawback of infinite heat propagation speed. Some of the known cases are derived as special cases. The Rayleigh-Bénard problem for a Maxwell-Cattaneo dielectric fluid is always less stable than that with classical heat conduction. It is shown that the destabilizing influence of the Cattaneo number is not attenuated by that of the dielectrophoretic force and vice versa, and that both second sound and electric forces change the aspect ratio of convection cells appreciably.