A global thermal model of the ARTEX facility, developed with the modeling tool CrysVUn, is presented. The model is validated with experimental data obtained under microgravity conditions during the TEXUS39 mission. Numerical studies are then reported, in which the effects of a rotating magnetic field are investigated during directional solidification of binary AlSi7 alloys. It appears that beyond a certain magnetic field strength a macrosegregation effect is resulting, leading to the development of a liquid channel inside the mushy zone. (C) 2004 Kluwer Academic Publishers.