Numerical investigation of initial stage of bubble rise

Asian Working Group- IAHR's Symposium on Hydraulic Machinery and Systems

Liu, M.^1 ; Tan, L.^1 ; Cao, S.L.^1 ; Wang, B.B.^1

State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing

100084, China^1

关键词: Bubble separation;    Multiphase model;    Numerical investigations;    Separation behaviors;    Simulation and analysis;    Strength differences;    Volume of fluid method;    Vortex structures;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/163/1/012121/pdf
DOI  :  10.1088/1755-1315/163/1/012121

来源: IOP

【 摘 要 】

The numerical investigation has been carried out on the initial stage of bubble free rise in still water. The simulation and analysis focus on the separation behavior of air bubbles. The Large Eddy Simulation (LES) and Volume-of-Fluid (VOF) methods are applied as the turbulence model and multiphase model, respectively. The bubble behavior and flow field are analysed to reveal the mechanism of bubble separation. The predicted results show that there exists a funnel shape air gathering on the injection hole of water tank, and the air bubbles are separated from the upper part gradually. The separation behavior of air bubble results from the back flow induced by vortex structure. The strength difference of vortex in both sides is the major cause of zigzag motions of streamlines and bubbles.