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

We study the effects of electrically conducting walls on the interaction between a perman-ent 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 measure-ment. Compared with insulating walls, the conducting walls lead to an increased drag force on the magnet. Except for low distances, the experimental results are satisfactor-ily reproduced in simulations using two different approximations of themagnetic field distribution.