Comparison between direct numerical simulation and k-ε prediction of the flow in a vessel stirred by a Rushton turbine

The flow in a baffled tank reactor stirred by a Rushton turbine was simulated at a Reynolds number of 7275. Two different approaches were used for the turbulent flow predictions, a direct numerical simulation and a simulation with the standard kappa-epsilon model. The flow patterns, the mean flow quantities, and the turbulent kinetic energy predicted by both methods were compared and showed a good overall agreement. Nevertheless, subtle differences were found in parts of the general flow field, e.g, the discharge flow of the impeller and in the distribution of turbulent kinetic energy. For most key features the DNS results are closer to experimental findings than the kappa-epsilon predictions.