Three-dimensional nonlinear waves at the interface between dielectric fluid in an external horizontal electric field

The nonlinear dynamics of the interface between dielectric fluids in a strong horizontal electric field is studied. It is shown that three-dimensional waves of small but finite amplitude can propagate without shape distortions either in a direction coinciding with the direction of the external field vector or in the direction opposite to this vector, along the interface of the fluids, whose density ratio is directly proportional to the ratio of their dielectric constants. For this particular case, an analytical description of the interaction of counterpropagating weakly nonlinear waves of arbitrary shape is given.