Electroconvective instability of thermogravitational flow in a vertical capacitor

The effect of such factors as the electrization of the fluid and the action of an electric field on the stability of the flow in a vertical layer with non-equal temperatures at the boundaries was investigated numerically and experimentally. Electrization of a non-uniformly heated poorly conducting fluid with a linear dependence of conductivity on temperature was used as a model for describing the electrical effects. The influence of electrical factors was taken into account by means of two parameters-the electrical Prandtl and Grashoff numbers (Pe and Ge, respectively). Numerics has shown that for small Pe, the low values of Ge correspond to stabilization of the flow expressed as an increase in the critical Grashoff number G. However as Ge increases, stabilization is replaced by destabilization and the critical G decreases to zero as Ge increases without bound. Experiments on electroconvective (EC) instability were carried out by measuring the thermal flux through borders of the vertical flat condenser. The material of electrodes and the liquid were chosen so, that the dependence of conductivity on temperature gave the primary contribution to an electrization of a liquid. The experiments have shown good agreement with theoretical results.