Convection in ferrofluids caused by forced diffusion in a magnetic field gradient

S. Odenbach

Institute fur Materialwiossenshaften, Bergishe Univresitat GH Wupertal, Munigstener Str. 10, D-42285 Wupertal, FRG

Abstract
We have investigated the behavior of a magnetic fluid under the influence of an inhomogeneous magnetic field gradient. We have measured the demixing of the fluid due to a forced diffusion of the magnetic particles in the field gradient. A temporary gradient in particle concentration antiparallel to the field gradient was predicted to drive a convective flow in the fluid [1]. This diffusion induced convection has also been observed using different techniques as neutron scattering, thermal anemometrie and inductive concentration measurements. The onset of the convective flow can be described with a model basing on a time dependent dimensionless parameter. Figs 6, refs 5.