Three-dimensional (3D) time-dependent numerical simulations were carried out in order to predict the oscillatory convection in a 20 kg silicon Czochralski melt under the influence of a cusp-magnetic field (40 mT). The numerical results are compared to experimental investigations of temperature fluctuations in the melt which were measured during the growth of a crystal with a diameter of 100 mm. The boundary conditions for the numerical simulation were taken from the experimental measurements. (C) 2002 Published by Elsevier Science B.V.