Ga transport in the melt during EFG Si crystal growth has been simulated within a 3D unsteady approach. The computations reveal reasons of effective redistribution of the impurity in the crystallization system. The computational results are compared with experimental data obtained in a new type of EFG furnace, designed for the growth of dodecagonally shaped silicon tubes of about 0.5 m diameter. To study the effect of 3D unsteady melt motion, the results are compared with 2D axisymmetric computations of Ga transport. (C) 2007 Elsevier B.V. All rights reserved.