Interfacial electrohydrodynamic instability: The Kath and Hoburg model revisited

A revision of the Kath and Hoburg model for the interfacial electrohydrodynamic instability in the case of two miscible fluids having identical properties but differing conductivities is attempted. Experiments performed by the same authors to validate their model show that the measured wave numbers do not correspond to the modes of maximum instability. In fact, the model is unable to give a preferred wave number. An analysis of the possible explanations for this discrepancy is made. In this Brief Communication the existence of a transient surface tension as the wave number selection mechanism is proposed.