Solidification of a binary metal alloy driven by a radial heat flux in presence of a rotating magnetic field: numerics vs. experiments

Rotating magnetic fields (RMF’s) are meanwhile widely used in metallurgy. The RMF eliminates flow asymmetries and allows for the control of heat and mass transfer, and hence of the evolving microstructure during solidification processes. In an extension of previous works, devoted to the unidirectional solidification in both constant and temporarily modulated RMF’s, we now analyze the solidification driven by a radial heat flux. The model geometry is a cylinder filled with a binary aluminum-silicon alloy. The outer walls of the cylinder are held on a constant temperature of 20°C while its lower surface is adiabatic. The top surface of the alloy is free.
The numerical simulations employ a hybrid solidification model which is implemented into a 2D Navier-Stokes solver based on the SIMPLE algorithm. We first re-investigate the spin-up problem, given by the simultaneous start of both cooling and acceleration of the melt, for different thermal conditions. Second, we compare the numerical results with corresponding experiments in the same model geometry which have been performed at the Helmholtz-Zentrum HZDR.