Convection of a ferrofluid in an alternating magnetic field

Parametric convective instability of a horizontal layer of a homogeneous ferrofluid under the action of an alternating magnetic field is studied. A case with rigid boundaries is considered. Convection thresholds are found. In an alternating magnetic field with a zero mean value, perturbations are found to have a synchronous character. These perturbations, however, can belong to different classes, because they depend on the temperature difference on the layer boundaries, the layer thickness, the frequency and amplitude of the alternating external field, and the physical properties of the ferrofluid.