Effect of the Mobility Parameter on the Oscillatory Electroconvection of Dielectric Liquids Subject to Strong Unipolar Charge Injection

Two-dimensional numerical calculations were carried out for the isothermal electroconvection in a dielectric liquid induced by the unipolar charge injection. In the dimensionless form, the system is mainly governed by the injection strength number C, the electric Rayleigh number T, and a mobility number M. A strong injection case with C = 10 was considered. Along with the increase in driving parameter T, oscillatory electroconvection occurs. Critical values of T corresponding to the onset of such oscillatory convection were shown to be highly dependent on M and were accurately determined. Some precautions, including the algorithm for the charge density equation, were taken to reduce the numerical diffusion and to ensure the reliability of our findings.