The recent development of the vertical gradient freeze (VGF) growth of GaAs focuses on the increase of process efficiency, a reduction of production costs and a simultaneous improvement of the crystal quality. To meet this technological and scientific challenge, different strategies are proposed, e.g. an increase of crystal size, simultaneous crystallization in multi-crucible furnaces or an increase of growth rate. To achieve these goals, an exact and permanent control of the melt flow is of crucial importance that is easily provided by traveling magnetic fields (TMF). The key aspect of the presented study is the well-defined control of the solid/liquid interface bending during VGF GaAs growth. Therefore, global simulations of the whole furnace are inevitable. Results of numerical simulations enable to properly adjust downward-directed Lorentz forces to achieve a significant decrease of the concavity of the solid-liquid interface. Compared to a reference crystal grown without TMF, a reduction of the interface deflection by about 30% was obtained. Gained experience from experiments in a single-crucible heater-magnet module (1-IMM) and numerical simulations led to the design of a novel multi-crucible HMM. (C) 2014 Elsevier B.V. All rights reserved