Multi-frequency electromagnetic stirring of liquid metals

In some applications of electromagnetic stirring of metals a characteristic flow pattern is requested in the melt which requires a certain volume force distribution. The possibilities to achieve such a volume force distribution by a suitable geometry and position of the stirrer are limited. More flexibility is obtained when the stirring is performed with two or more magnetic fields traveling with different velocities in different directions. It is shown in the present paper that such a stirring can be realized with a conventional stirrer by feeding its three-phase winding with a current made up by superposition of two or more currents with different frequencies and traveling directions.