Using numerical simulation, we have studied the Si1-xGex Czochralski (CZ) growth with 3 at% initial melt Ge content. Global heat transfer computations in the entire CZ system and 2D or 3D computations of melt turbulent convection in the crystallization zone have been made. The computed crystallization front shape is compared with respective experimental data obtained by X-ray topography. Unsteady transitions of the melt flow are studied to analyze the stability of the crystallization process. (C) 2004 Elsevier B.V. All rights reserved.