NONLINEAR STABILITY PROBLEM OF A FERROMAGNETIC FLUID WITH SURFACE-TENSION EFFECT

A nonlinear stability analysis is developed to study the buoyancy-surf ace tension effects in a ferromagnetic fluid layer which is heated fro m below. The free surface is assumed to be flat and non-deformable. By considering full nonlinear terms in the governing equations it is sho wn that the nonlinearities can be controlled by a generalized energy f unction. The qualitative behaviour of the stability boundary, under th e effects of three forces, is computed as a function of its parameters . In the absence of a magnetic field, the results of Davis are recover ed. Numerical results pertaining to the optimal stability boundary are obtained for both the energy and linear theories and the existence of possible subcritical instabilities is pointed out.