Electromagnetic interaction of a small magnet and liquid metal flow in a pipe with insulating or conducting walls

O. Kazak¹ - Ch. Heinicke² - Th. Wondrak³ - Th. Boeck¹

¹ Institute of Thermodynamics and Fluid Mechanics, Ilmenau University of Technology P.O.Box 100565, 98684 Ilmenau,Germany
² Department of Applied Mechanics, Aalto University, P.O.Box 14300, 00076 Aalto, Finland
³ Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany

Abstract
We study the effects of electrically conducting walls on the interaction between a permanent magnet and a liquid-metal flow in a cylindrical pipe using experiments and numerical simulation. The problem is motivated by Lorentz force velocimetry, where the drag force on the magnet due to the induced eddy currents in the flow is used for flow measurement. Compared with insulating walls, the conducting walls lead to an increased drag force on the magnet. Except for low distances, the experimental results are satisfactorily reproduced in simulations using two different approximations of the magnetic field distribution. Tables 2, Figs 10, Refs 8.