Numerical Study of Pure Electroconvection and Combined Electro-thermo-convection in Horizontal Channels

Abstract

Electrohydrodynamic effect on natural convection in horizontal channels is investigated from a numerical point of view. The EHD effect is induced by narrow strip electrodes placed at the bottom wall of the channel. The channel is subjected in a first stage only to the electric forces, and in a second stage to the simultaneous action of a temperature gradient and an electric field. The interactions between electric field, flow field and temperature field are analyzed. It can be concluded that charge density distribution, flow pattern and temperature distribution are substantially affected by the arrangement of the electrodes; in fact four different arrangement were treated. The effect of pure electroconvection on charge density distribution and on flow pattern was studied. A periodic flow corresponding to particular values of electric Rayleigh was observed, then the impact of combined electro-thermo convection on heat transfer was undertaken in a second step and it was noted that the optimum arrangement of the electrodes provides an increase in heat transfer of up to 13%. The effect of the applied electric forces is also studied in order to highlight the importance of putting compromise between the supplied voltage and arrangement of the electrodes. Finally, a study of optimized configuration of electrodes was achieved.