The dynamics of bubble formation through aeration with liquid cross-flow and its numerical simulation

A 3-dimensional numerical computation is carried out to simulate the process of bubble formation through aeration in a plug-flow aeration tank. The two-phase flow in aeration tank is treated as a single fluid with variable properties and the shape of bubble is traced by the level set method. An explicit time-marching ICE (Implicit Continuous-fluid Eulerian) algorithm is employed to solve the governing equations. The effects of the liquid cross-flow on dynamics of bubble formation in water are studied in detail. The simulation results on the bubble shape are qualitatively in good agreement with experimental observations in the literature. The results show that the liquid cross-flow has a strong impact on the bubble generation. When compared to bubble formation under quiescent liquid, the bubble grows downstream along the tilted axis, the bubble formation time tends to decrease noticeably, and the bubble formed has significantly smaller size due to the drag force acting on the forming bubble exerted by the liquid motion.