INSTABILITY OF A CHARGED INTERFACE OF 2 IMMISCIBLE VISCOUS-LIQUIDS WITH CHARGE RELAXATION TAKEN INTO ACCOUNT

On the basis of an analysis of a derived dispersion relation, it is de monstrated that there can be two different types of instability relati ve to th free charge of a charged, planar interface between two viscou s immiscible liquids with finite electrical conductivity in a gravitat ional field. For large values of the surface charge density, depending on the viscosities and ratio of conductivities of the media, one can observe either an aperiodic (of the Tonks-Frenkel type) or oscillatory instability of the interface. Increasing the viscosity of the lower l iquid leads to a substantial drop in the increments of the mentioned i nstability types and alters the critical conditions for manifestation of the oscillatory instability, whereas varying the viscosity of the u pper surface has only a very weak effect on these characteristics. (C) 1998 American Institute of Physics. [S1063-7842(98)00309-2].