Swirling, recirculating flow driven by a rotating magnetic field

D. J. Short - P. A. Davidson

Department of Mechanical Engineering, Imperial College of Science, Technology and Medicine, Exibition Road, London SW7 2BX, England, UK

Abstract
In this paper we investigate the swirling flow of liquid metal in an axisymmetric cavity generated by a rotating magnetic field. Previous theoretical work has suggested that for such a flow, the angular momentum must always be independent of axial position, whatever the distribution of the Lorentz force. However, until now, this had not been confirmed experimentally. Mean flow velocity measurements have been made in two different axisymmetric basins, a hemisphere and a 45° cone, and have confirmed that the angular momentum is indeed independent of axial position, even when the body force varies quite rapidly along the axis of symmetry. In short, our experiment demonstrates that the swirl behaves as a Taylor column. Form this simple (yet profound) result we show that it is the total applied magnetic torque alone which determines the swirl distribution, and not the particular details of the body force distribution. Figs 13, Refs 5.