Large eddy simulation of bubble-driven plume with finite bubble void fraction*

Eulerian-Eulerian large eddy simulation (LES) approach is widely used for modeling bubble-driven plumes in many environmental and industrial applications. Under low bubble void fraction condition, bubbles can be treated as a dispersed phase for which an Eulerian transport equation is solved to compute the evolution of bubble concentration in the turbulence flow, and effect of bubbles on the flow field is added to the momentum equation through a buoyancy force term. This allows fast computation of the plume evolution by avoiding significant modification to the flow solver. However, under many practical conditions the bubble void fraction is not negligible, requiring additional modifications to the flow solver to account for other effects due to finite bubble void fraction. In this study, an LES model for bubble-driven plume with finite void fraction is developed. Preliminary tests for lab-scale cases are conducted and compared with those obtained from an LES model with low-void-fraction approximation. The new model is shown to efficiently capture the effect of non-negligible bubble void fraction on plume characteristics without significantly increasing the computational cost.