Rotational Brownian motion of a colloidal magnetic particle in a ferrofluid under the influence of an external magnetic field may give rise to a noise induced rotation of the particle due to the rectification of thermal fluctuations. Via viscous coupling the associated angular momentum is transferred to the carrier liquid and can be measured as a macroscopic torque. In the present contribution we study the case of a rotating ferrofluid and elucidate the interplay between the ratchet effect and the non-zero vorticity of the flow.
Print ISSN: 0942-9352
Volume: 220, 02/2006
Pages: 225 - 233