Effect of Thermal Modulation on the Onset of Electrothermoconvection in a Dielectric Fluid Saturated Porous Medium

An electroconvection in a horizontal dielectric fluid saturated with a densely packed porous layer is investigated under the simultaneous action of vertical electric field and vertical temperature gradient when the walls of the layer are subjected to time periodic temperature modulation. The dielectric constant is assumed to be a linear function of temperature. A regular perturbation method based on small amplitude of applied temperature field is used to compute the critical values of Rayleigh number and wave number. The shift in the critical Rayleigh number is calculated as a function of frequency of modulation, electric Rayleigh number, Prandtl number, and Darcy number, and their effects on the critical Rayleigh number are discussed. The situations which are favorable for the design of artificial organs without the side effect of hemolysis are explained.