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Flows of ferromagnetic fluids (colloidal suspensions) are obtained by coupling to the suspended single-domain particles with a rotating magnetic field. It is shown that very high rotation rates are possible by this technique. Nonmechanical torque-driven flows represent a hitherto unexplored area in the physics of fluids that has interesting potential technological application. A ferromagnetic pump based upon the present principle could be of great value in fluidic systems and open up new applications in space, ocean, biological and other environments.

Recent publications have dealt with the nature and applicationsl-II of colloidal suspensions of single-domain particles that behave as continuum ferromagnetic fluids. In these earlier reports, ferrofluid phenomena such as levitation and magnetocaloric energy conversion have utilized time-invariant spatially inhomogeneous magnetic fields to generate the necessary …