Numerical Study of Electro-thermo-convection in a Differentially Heated Cavity Filled with a Dielectric Liquid Subjected to Partial Unipolar Injection

The Coulomb force applied by an electric field on any charge present in a dielectric liquid may cause fluid motion. At high applied electric fields in an insulating liquid, electric charge carriers are created at metallic/liquid interfaces, a process referred to as ion injection, and result from complex electrochemical reactions. In this article we deal with the problem of electro-thermo convection in a dielectric liquid placed in a square cavity and subjected to the simultaneous action of a thermal gradient and an electric field. Thus, the aim is to analyze, from a numerical point of view, the evolution of flow structure, charge distribution and heat transfer in the case of a strong injection. The computational domain is as follow: the vertical walls are differentially heated; the horizontal walls are adiabatic except a part of the bottom wall (33% of the total length) is defined as the injecting electrodes. Three possible configurations are treated depending on the location of the injecting electrode: so we identify an injection from the left, from the middle and finally from the right. The results show that a partial injection can enhance heat transfer up to 24%. The flow structure in terms of streamlines, distribution of electric charge density and thermal field is highlighted. The effect of various system parameters in particular the injection zone locations, the electric Rayleigh number is investigated as well.