Numerical study of the heat transfer and electro-thermo-convective flow patterns in dielectric liquid layer subjected to unipolar injection

Abstract

In this article we study the electro-thermal convection in a dielectric liquid layer placed between two electrodes and subjected to the simultaneous action of an electric field and a thermal gradient. The full set of equations describing the electro-thermo-convective phenomena is directly solved using a finite volume method. We first heat the liquid from below at time t = 0, wait for the thermal steady state and then inject the electric charges by applying the electric potential. The development of the electro-convective motion is analysed in detail in two cases: 1) strong injection from the lower electrode, 2) strong injection from the upper one. We also study the heat transfer enhancement due to electro-convection. The evolution in time of the Nusselt number Nu for different combinations of the two usual non-dimensional parameters associated to the electro-thermo-convection phenomena (Rayleigh number Ra and the electrical parameter T ) is also given and analysed. We study the electro-thermal convection in dielectric liquid layer under action of electric field and thermal gradient. The relevant equations are solved by finite-volume method. The convective motion and heat transfer is analysed for strong injection from the lower and upper electrode. We show that: electro-convection significantly increases heat transfer; Nusselt number is independent of the Rayleigh number; the difference between both cases of injection is negligible.