Density-based turbulence damping at large-scale interface for Reynolds-averaged two-fluid models

The overestimation of turbulence near large-scale interfaces in Reynolds-averaged per-phase turbulence models is a well-known problem. Herein, this is addressed by analyzing the turbulence transport equations and identifying the intrinsic limitation in the formulation of per-phase turbulence models for stratified flow. A novel density-based turbulence damping approach is proposed and compared to a conventional phenomenological damping model and a mixture model for pressurized co-and countercurrent as well as gravity-driven stratified air-water flows. The novel approach performs well for all test cases. It is shown that the turbulence damping in the less dense phase is more important than that towards the denser phase. The density-based damping approach leads to more realistic turbulent kinetic energy profiles across the interface region compared to typical existing phenomenological damping approaches. Further, the novel approach does not rely on calibration parameters nor interface indicator functions and is thus well suited for further development of per-phase generalized models. (c) 2021 Published by Elsevier Ltd.