Comparison of Different Techniques for Modelling of Flow Field and Homogenization in Stirred Vessels

Application of different simulation techniques to predict flow field and tracer distribution in a stirred tank was investigated. Impeller motion was explicitly modelled using the Multiple Reference Frames technique (steady-state simulation of the impeller motion) and the Sliding Mesh model (unsteady-state simulation), implemented in the FLUENT code. Simulations were performed for turbulent flow regime using the standard k-e turbulence model. Already, using the steady-state simulation approach fairly good prediction of the tracer homogenization in the vessel stirred with the pitched blade turbine was obtained. Simulation results were further improved using the Sliding Mesh model. However, the use of dynamic simulation was about 100 times more time-demanding in contrast to simulation based on the Multiple Reference Frames with the “frozen” flow field.