In the present paper, a numerical method is described which allows in principle an easy coupling of a local 3D model of melt convection to a global 2D model of the whole crystal growth facility. The global 2D model is based on a hybrid scheme consisting of a combination of unstructured and block-structured meshes. The grid of the local 3D model of the melt region is directly generated in the global 2D model by a virtual expansion of the 2D block-structured mesh in the third azimuthal dimension. The local 3D model can be fully coupled to the global 2D model. Two strategies of the 2D-3D coupling are presented. The first one is based on the transfer of the temporally and azimuthally averaged results of the local 3D model to the global 2D model. In the second strategy, both models are executed at the same time scale and the azimuthally averaged heat flux in 3D is balanced with the global 2D heat transport only at the boundary of the 3D domain. Both strategies, which are tested for a realistic Czochralski configuration, are compared in terms of efficiency. (C) 2007 Elsevier B.V. All rights reserved.