Buoyancy-driven flow plays an important role in the solidification of multi-crystalline silicon in rectangular crucibles and has been subject of recent investigations (Miyazawa et al., 2008 [1,2], Delannoy et al., 2007 [3]). Though the driving force due to the slightly curved temperature profiles is small, the large dimensions of industrial-scale crucibles can lead to complex flow. Here we present transient 3D calculations of melt convection. Thermal boundary conditions were either given analytically or resulted from 3D global calculations. The influence of the shape of the thermal boundary conditions, the mesh type and the flow model on the melt flow has been studied. Furthermore, we applied Lorentz forces to the melt system, created by travelling magnetic fields (TMFs). Preliminary results on the time evolution of the flow patterns in the presence of TMFs will be shown. (C) 2009 Elsevier B.V. All rights reserved.