Viscous dominated interfacial electrohydrodynamic instability in polar geometry

Interfacial electrohydrodynamic instability between fluid components with identical permittivity and viscosity but disparate conductivities for viscous dominated flows in polar geometry is described by an experiment and linear instability theory. Theoretical results are in agreement with a corresponding flat interface, distant boundary model for high mode numbers, and geometrically altered for mode numbers low enough for effects of boundary proximity and equilibrium interfacial curvature to be appreciable. Retardation and enhancement of growth rate are found in correspondence with radially decreasing and increasing conductivity, respectively. Experimental observations confirm a most rapidly growing mode for the latter and apparent lack of one for the former case, in agreement with the nature of the theoretical description.