Comparison between Direct Numerical Simulation and k–ε–Model Prediction of the Flow in a Vessel Stirred by a Rushton Turbine

Abstract

The k-ɛ model is the most prevalent turbulence model in the numerical simulation of stirred vessel flows. Despite the fact that many other turbulence models—such as the κ-ω model and the RNG κ-ɛ model—have been introduced to improve the κ-ɛmodel, it has remained the most frequently utilized model for routine investigations in industry. The reason for this predominance is that the κ-ɛ model has been quite successfully applied to many complex flow problems. Moreover, the weaknesses of the model are relatively well known and can be accounted for. The comparison of the large-scale flow field shows a good overall agreement of the observed flow features for both types of simulations. On the other hand, close comparison revealed differences between DNS and κ-ɛ simulations where the DNS predictions were almost always closer to experimental results. The results for the turbulent kinetic energy κ also show some evidence of better agreement between experiment and DNS but it is not completely clear right now how reliable the information for turbulent kinetic energy is.