Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb-Sn alloys from a water cooled copper chill. A rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. Profiles of the velocity in the liquid phase were determined by means of Ultrasound Doppler velocimetry (UDV). The forced convection causes distinct modifications of the temperature and concentration field.