Sammendrag
Proper turbulence modelling of bubble plumes is critical for accurate simulation of liquid phase and bubble dynamics. The k-epsilon turbulence model is widely used. However, the model is unsatisfactory due to not accounting for the following physics: (1) turbulence damping in the vicinity of a free surface; (2) turbulence modifications created by non-uniform distribution of the bubbles; (3) extra turbulence agitation by bubble wakes. In order to remedy these deficiencies, an enhanced turbulence model has been developed, followed with application to a literature experiment of a gas-stirred ladle. The model framework is an Eulerian-Lagrangian large scale interface-capturing computational fluid dynamics (CFD) approach, coupling a volume-of-fluid model with discrete phase model. The implications of each physical process in turbulence modelling are investigated. The detailed model-experiment comparisons indicate that the enhanced turbulence model allows improved representation of the physics of bubble plumes, as well as the transport phenomena at, and close to, the free surface.