A novel generalized multifluid modelling approach for the simulation of multiphase flows: model development and validation

Multiphase gas-liquid flows exist in a large variety of flow regimes with interfaces that often span over a broad range of length scales. This paper introduces the generalized multifluid modelling approach (GEMMA), developed to predict the complex multiphase regimes where dispersed and large scale interfaces co-exist. The GEMMA solver introduces interface resolving capabilities inside a multifluid framework, by selectively applying a dispersed or a large interface multifluid formulation based on the local interfacial scale. Validation of the model against fundamental segregated and dispersed flow conditions is achieved. These include a rising bubble in liquid at rest, where the model achieves an accuracy comparable to interface resolving techniques, a stratified laminar flow and a bubbly pipe flow, where the model operates in the dispersed regime. In the final part, the solver is used to predict a stratified turbulent flow, where modelling of the turbulence at the interface is mandatory for the accurate prediction of the phase velocities and distribution.