Non-linear plane perturbation in a non-ohmic/ohmic fluid interface in a   vertical electric field
  The stability of a non-ohmic/ohmic fluid interface in the presence of a constant gravitational field and stressed by a vertical stationary electric field with unipolar injection is studied, focusing on the destabilizing action of the electric pressure when charge relaxation effects can be ignored. We use a hydraulic model, whose static equilibrium condition is written and analysed as a function of the ohmic fluid conductivity when subjected to a non-linear perturbation. The combined action of the polarization and free interfacial charges on the pressure instability mechanism is also analysed. The results show some important peculiarities of the fluid interface behaviour in the presence of a stationary space charge distribution generated by unipolar injection in the non-ohmic fluid. 
Francisco Vega Reyes