Numerical simulations were carried out in order to predict the oscillatory convection of a silicon melt induced by natural convection and forced convection due to crucible and crystal rotation in an industrial Czochralski configuration. The predicted thermal field is compared to experimental observations of the thermal field and temperature fluctuations in the melt. Temperature fluctuations have been measured during a crystal growth process using a thermocouple. The governing equations were numerically solved using the code STHAMAS 3D, based on a block-structured finite-volume Navier-Stokes solver. The three-dimensional simulation of flow was done without any turbulence model.