We present an updated version of the combined 2D/3D model of heat transfer and turbulent melt convection for industrial Czochralski (CZ) crystal growth. The 3D computational domain consists of silicon melt, crucible and crystal, and is extended by including gas blocks. To provide boundary conditions for the 3D domain, global heat transport is calculated within a 2D steady approach. Several computed melt/crystal interface geometries are compared with available experimental data for 100 and 300 mm diameter CZ crystals. The temperature distribution along the melt/crucible boundary and unsteady temperature fluctuations in the melt bulk are compared with the respective measurements. The computations are performed using an improved version of the crystal growth simulator (CGSim) program package allowing 3D unsteady analysis with high approximation orders. (C) 2004 Elsevier B.V. All rights reserved.