Experiments on liquid metal flow induced by a rotating magnetic dipole

The flow of liquid metal induced by rotation of a cylindrical permanent magnet, which is magnetized normal to the axis, has been investigated during model experiments. Rotation of the magnetic cylinder induces a rotating magnetic field in the surrounding space and consequently the vortical electrical current in the conducting medium. Flow in a rectangular pool of liquid metal was investigated by measuring the characteristic flow velocity as a function of angular velocity of the magnetic cylinder and distance from the axis of the magnet. Order-of-magnitude analysis of the induced electromagnetic force in the liquid metal pool shows that both the pressure gradient and the vorticity are produced, generating a complex melt motion. Combining two cylinders in a coupled rotating system allowed to achieve completely different flow patterns. Coupling of the cylinders was achieved by magnetic forces or by mechanical coupling. The variety of achievable flow patterns and magnitudes of the flow was video recorded. Suggestions are presented to apply this type of permanent magnet systems as melt stirrers or pumps in practical tasks.