The European Physical Journal B (EPJ B)

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Eur. Phys. J. B 18, 337-341

Magnetic permeability of a diphasic flow, made of liquid gallium and iron beads

A. Martin¹ - P. Odier¹ - J.-F. Pinton¹ - S. Fauve²

¹Laboratoire de Physique, École Normale Supérieure, 46 Allée d'Italie, 68007 Lyon, France
² Laboratoire de Physique Statistique, École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
pinton@ens-lyon.fr

Received 6 March 2000 and Received in final form 13 July 2000

Abstract
Magnetohydrodynamics studies in laboratory experiments have long been restricted to low magnetic Reynolds number flows, mainly as a result of the very high magnetic diffusivity $\lambda = 1/\mu\sigma$ of common conducting fluids ( $\mu$ is the fluid's magnetic permeability and $\sigma$ its electrical conductivity). The best conductivities are found in liquid metals which have a unit magnetic permeability, relative to vacuum. We show experimentally that a suspension of solid particles with a high magnetic permeability in a liquid metal yields an effective medium that has a high electrical conductivity and an enhanced magnetic permeability. The dispersion of the beads results from the turbulent fluid motion. The range of accessible magnetic Reynolds number can be increased by a factor of as much as 4 in our experimental setup.

PACS
47.65.+a Magnetohydrodynamics and electrohydrodynamics - 75.50.Mm Magnetic liquids - 47.55.Kf Multiphase and particle-laden flows