Numerical Study of Oscillating Melt Flows and Its Solute Transport Driven by Electromagnetic Force around Dendrite

Abstract

Numerical simulations of oscillating flows of molten metal were carried out. These flows were driven by electromagnetic force under imposition of static magnetic field and alternating electric field. Solute transport around a dendrite was calculated simultaneously with the flow field. Results of simulations clarify effects of the electromagnetic oscillating flows on the solute transport when solute condensation occurs in liquid phase around the dendrite. Boundary layer of the oscillating flow is similar to Stokes layer. In the vicinity of the tip of the primary arm (or the tertiary arm), a vortex is generated from this shear layer every half period. These vortices blow up the solute and hence solute transport is enhanced. Simulation results of various conditions suggests the optimum Womersley number exists while the primary-arm Reynolds number is required to be much greater than one. Five times enhancement of solute transport is obtained in a typical case where Womersley number is 8.6 and the primary-arm Reynolds number is 14.