AuthorJ Ma, AA Oberai, DA Drew, RT Lahey Jr., and MC Hyman
TitleA comprehensive subgrid air entrainment model for RaNS modeling of bubbly free surface bubbly flows
JournalJournal of Computational Multiphase Flows
Volumeto appear
AbstractThe simulation of free surface bubbly ows using a two- uid model remains a challenging problem in part due to the lack of a comprehensive air entrain- ment model that can predict the rate and location of air entrainment for a wide range of ows. In this study we derive a sub-grid model and implement it in a computational multiphase uid dynamics (CMFD) framework to solve the Reynolds-averaged two- uid equations. We assess the performance of our model in simulating bubbly ows underneath a plunging liquid jet and a hy- draulic jump while varying the characteristic velocity. We compare the void fraction predictions with their experimental counterparts and conclude that the air entrainment model and the two- uid modeling approach yield accurate results everywhere for the plunging jet and in the turbulent shear layer for the hydraulic jump. The inability of the proposed approach to recover the high void fraction in the roller region of the hydraulic jump is attributed to the failure of RaNS model to resolve the large coherent vortices observed in this region.