Longwave Interface Instability In Two-Fluid Vibrational Flow

We consider longwave mode of the interface instability in the system comprising of two immiscible fluid layers. The fluids fill out plane horizontal cavity which is subjected to horizontal harmonic vibration. The analysis is performed within the framework of "high frequency of the vibration" approximation and the averaging procedure. The nonlinear equation (having the form of Newton's second law) for the amplitude of interface deformation is obtained by means of multiple scales method. It is shown that (in addition to previously detected quasistationary periodic solutions) the equation has a class of quasistationary solitary solutions.