A critical assessment on the use of k– ε turbulence models for simulation of the turbulent liquid flow induced by a Rushton-turbine in baffled stirred-tank reactors

Abstract

The stirred-tank reactor (standard configuration) equipped with a Rushton turbine is theoretically investigated by solving continuity, momentum and turbulence quantity balance equations. Modelling approaches for the Rushton turbine and further important modelling aspects concerning the stirred tank are discussed. In this work the Rushton turbine is modelled with the aid of experimental data. In combination with this special modelling approach for the stirrer, the accuracy of three ad hoc applicable k– ε turbulence models in predicting mean flow and turbulence quantities is tested with the aid of three-dimensional simulations. The differing simulation results are compared with experimental data. None of these k– ε models performs satisfactorily without modification. However, in considering experimental observations and the general construction of k– ε models it is possible to optimize one special k– ε model. Good agreement can then be achieved between measured flow details and the simulation results for vessels and impellers of different geometry.