Numerical study of the electro–thermo-convection in an annular dielectric layer subjected to a partial unipolar injection

Abstract

This article deals with the problem of electro–thermo-hydro-dynamic (ETHD) in a dielectric liquid placed between two horizontal isothermal coaxial cylinders and subjected to the simultaneous action of a thermal gradient and an electric field. The full set of equations describing the combined ETHD flow is directly solved using the control-volume method. The effect of electroconvective motion was investigated in details in the case of strong unipolar injection from the half bottom of the inner cylinder. We focused mainly on enhancing the heat transfer by unipolar injection of electric charge in the dead zone (bottom area) of the annular space.The results show the emergence of a multicellular flow in this dead zone which enhances the heat transfer up to 170%. The flow structure in terms of stream lines, distribution of electric charge density and thermal field is highlighted. The effect of various system parameters in particular the radius ratio, the electric Rayleigh number is investigated too.