(162g) Numerical Study of Bubble Dynamics with Advanced Lattice Boltzmann Simulation

In this study, the dynamics of bubbles will be simulated using an advanced lattice Boltzmann method (LBM). The new LBM takes advantage of both the adaptive mesh refinement (AMR) technique and the multiple relaxation time (MRT) algorithms, so that bubbles with large deformation and high Reynolds number can be simulated. High grid resolution is applied near the bubble surface as well as the regions with high vorticity in order to improve accuracy. The MRT technique is found to greatly enhance the numerical stability at low viscosities, and consequently enables the study of high-Reynolds number bubble flows that are relevant to many real-world problems. The computation results for flow field around buoyant rising bubbles under various conditions are presented. In particular, the wake structure of the bubbles as a result of their deformation and high Reynolds number is analyzed. Different patterns of bubble motion are observed in the simulations, including both rectilinear and oscillatory rise. The bubble trajectory is obtained from the simulation, and the relation between the transient forces on the bubble and the flow field is discussed. It is found that the wake structure has important effects on the motion of the bubble. Simulations are also carried out to investigate the hydrodynamic interactions between bubbles, which affect the bubble shape and velocity through the change of local flow field, particularly through the bubble wake interaction.