Potseluiev S. Мultiparametric excitation of internal and surface waves in ferrofluids

The problem of parametric instability for ferrofluid layers at periodic actions of magnetic fields of different orientation and vertical mechanical vibrations is studied. Cases of ferrofluid systems with unbounded free surface and with the interface between two fluids, bounded by solid walls, are considered. Such physical factors as viscosity of fluids, nonlinear magnetization law, the existence of gravitational and capillary forces were taken into account. Boundaries of instability regions in the space of physical parameters of considered systems are calculated. Parametric instability corresponds to the appearance of surface waves for incompressible ferrofluid layers. Regions of instability for compressible magnetizable fluids correspond to the occurrence of acoustic waves due to excitation of volumetric parametric resonance by oscillating magnetic field.