Accelerated VGF-growth of 4 in. GaAs ingots by downwards traveling magnetic fields (TMFs) was investigated numerically. The focus was led on the feasibility of control of s/l interface shape by Lorentz forces in the range of crystal growth rates from 3 to 9 mm/h. Particularly, the aim of this study was to derive a method for a prediction of electro-magnetic parameters of TMF such as frequency, phase shift and AC amplitude that provide maximal improvement of interface deflection towards convex morphology during the fast growth. A typical VGF furnace equipped with a KRISTMAG (R) internal heater-magnet module was used for the simultaneous generation of heat and TMF. The revealed deflections were correlated with dimensionless numbers: Grashof Gr, Stephan Ste and Forcing number F. With an increase of F while holding Grand Ste numbers constant, transition through the point of maximal positive deflection was marked by a lift of the stream function vortex from the region of triple point upwards. (C) 2013 Elsevier B.V. All rights reserved.