Bubble-induced turbulence: Comparison of CFD models

Modeling of bubble-induced turbulence in dispersed gas-liquid multiphase flow is an important but still unresolved issue. Aside from its intrinsic interest, turbulence in this type of flow has a strong impact on other important processes like turbulent dispersion of the bubbles and bubble-coalescence and -breakup and thus is a central part of the overall model. Current state of the art is to simply add an extra bubble-induced contribution to the effective viscosity. In more refined approaches source terms are added to the single phase two-equation turbulence models, but no agreement on the precise form of these terms has been reached yet. We here report a comparison of different models of this type, some of which have been used previously and some of which are new. A set of reference data has been selected from the literature that provides a first assessment of the relative merits of the state of the art and different advanced approaches. The need for further research is evident and the most promising directions are identified. (c) 2013 Elsevier B.V. All rights reserved.