Lattice Boltzmann simulations of the rising bubble flows

Recently, the lattice Boltzmann method (LBM) has gained much attention for its ability to simulate fluid flows, and for its potential advantages over a conventional CFD method. The key advantages of LBM are, suitability for parallel computations, absence of the need to solve the time-consuming Poisson equation for a pressure, and an ease with the way multiphase flows, complex geometries and interfacial dynamics may be treated. The motion of the bubbles in a liquid has been the focus of both academic and practical interest. The central problem is the relationship between the rise velocity, bubble shape due to the interface deformation and flow field. The buoyancy effect due to density difference in the two phase flows is characterized with Eotvos and Morton numbers. In this study, a single bubble rising under a buoyancy is simulated with the method proposed by Zheng et al. The simulation results are compared with those of a previous numerical method such as VOF. The results by LBM are also presented for the coalescence of the bubbles. The main objective of the present work is to establish the lattice Boltzmann method as a viable tool for the simulation of multiphase or multi-component flows