Flows and Wave Propagation in Ferrofluids

The dynamic behavior of magnetically polarizable fluids (ferrofluids) is considered in two instances differing in the dependence of the fluid magnetization on temperature. When the magnetization can be regarded as temperature independent, the influence of the magnetic field on the force distribution acting on a submerged body is demonstrated, the flow pattern of the associated ordinary fluid dynamics problem remaining unaffected. In the other instance, when the temperature dependence of the magnetization must be considered, the question of thermal stability of the ferrofluid is considered and the appropriate magnetic Rayleigh number and its influence are determined. Furthermore, it is shown that small disturbances in a ferrofluid are quickly damped so that vorticity generated by the thermomagnetic interaction for such disturbances does not propagate.