Comparison of stirring efficiency of various non-steady magnetic fields during unidirectional solidification of large silicon melts

A numerical comparison of various techniques of non-steady magnetic stirring, such as travelling (TMF), rotating (RMF), alternating (AMF) and carousel magnetic fields (CMF), during unidirectional solidification of large rectangular silicon melts of 700kg was performed. The comparison was focused on the time required to homogenize the distribution of a point wise released tracer in the melt. All studied magnetic fields showed identical magnetic screen and interaction parameter Rω=80.3 and Nmag=7.9×10−6, respectively. The Lorentz forces were generated in KRISTMAG® heater magnet modules (HMM) positioned at the side or bottom of the silicon melt container. Stirring progress was studied by tracking the formation of the concentration field of the passive tracer in already fully developed melt flow. Results revealed the superiority of the CMF concept independent of the point of injection. ► Numerical study of directional solidification of 700kg silicon. ► Comparison of stirring efficiency of various unsteady magnetic fields. ► The most efficient stirring was achieved by CMF, followed by RMF and TMF.