Taylor-vortex flow of ferrofluids in the presence of general magnetic fields

Abstract

The influence of magnetic fields on the flow of a magnetic fluid in the gap between two concentric rotating cylinders is investigated by linear analysis and explicit finite-difference numerical solution of the full nonlinear time-dependent field equations. An oscillatory instability of the primary flow towards Taylor vortices predicted by Vislovich et al. (1986) on the basis of a linear analysis for a superposition of axial and radial magnetic fields is confirmed. Detailed investigations show further that this instability manifests itself as a travelling pattern which can be found also in a finite system. In a wide region in parameter space nonaxisymmetric flow patterns appear as the primary instability. An axial-azimuthal magnetic field generates an axial flow, sustaining a net mass transport in axial direction.