The paper presents an investigation of the turbulent flow features in a CZ crystal growth system with a horizontal DC magnetic field by 3D mathematical modelling. A laboratory model with InGaSn eutectic and with a 20" crucible is considered. The model corresponds to an industrial silicon crystal growth system. A 3D model for the scalar potential induced in the melt by a horizontal DC magnetic field is implemented in the HD program package CFD-ACE(V2003) together with the corresponding boundary conditions. For 3D HD calculations, moderate grids and the RNG kappa-epsilon turbulence model are used. The features of the flow and the temperature field structure in different cases (only thermogravitational convection, flow with rotation influence) under the magnetic field are investigated. It is shown that the flow and temperature distributions in all cases are strongly influenced by the magnetic field of 0.08-0.16 T. The crucible and crystal rotation together with the horizontal DC field creates flow and temperature distribution with a very complicated 3D structure. (C) 2003 Elsevier B.V. All rights reserved.