Nonlinear oscillations of molten silicon drops in electomagnetic levitator

Nonlinear oscillations of molten silicon drops in an electromagnetic levitator under microgravity are numerically investigated. The electromagnetic field and the magnetic pressure on the drop surface are calculated by the surface integral method assuming that the skin depth is much smaller than the drop radius. The Galerkin finite element method in combination with the Lagrangian technique is used to analyze the moderate-amplitude axisymmetric oscillations of the silicon drops on which the magnetic pressure acts. The effect of the electric current ratio of the heating coils to the levitation coils on the frequency of the oscillations is evaluated for molten silicon drops released from either an initially prolate spheroid configuration or four-lobed spherical harmonic configuration. The numerical results show that, in the former case, the frequency decreases with the current ratio. Also, for the latter, the dynamics of the second mode becomes dominant as the current ratio increases, because the inward magnetic pressure from the heating coil increases.