The onset of electrothermal convection in nonpolar liquids on the basis of a dissociation-injection conductivity model

The onset of convection for a layer of nonpolar liquid subjected to an adverse thermal gradient and intense electric field is examined. The electrical conductivity is determined via a recent physiochemical model based on dissociation and injection charge generation. Convective instabilities and overstabilities are predicted as a function of strength of injection C and residual conduction C₀. Physical and mathematical arguments show that for values of C bigger (smaller) than 2√2C₀ , the regime is approximately injection dominated (conduction dominated). It is also shown that dissociation always plays a stabilizing role, which is contrary to the injection which can have either a stabilizing or a destabilizing effect due to its indirect coupling with thermal perturbations