Closure models for turbulent bubbly flows: a CFD study

For practical applications the Euler-Euler two-fluid model relies on suitable closure relations describing interfacial exchange processes. In dispersed gas-liquid multiphase flow, bubble-induced turbulence is one such process for which a satisfactory model is still not available. A common approach to its solution is to add source terms to the single phase two-equation turbulence models. Here we report a comparison of different models of this type some of which have been used previously, some of which are new. To qualify the validity of the different models a set of reference data has been selected from the literature. Together with a suitable model for the bubble forces the most promising variants can be identified. Special attention in this respect is given to the wall force. Guidelines for modeling bubbly turbulence are proposed and needs for further research identified.