Hydrodynamic investigation of multiple rising bubbles using lattice Boltzmann method

Hydrodynamics of multiple rising bubbles as a fundamental twophase phenomenon is studied numerically by lattice Boltzmann method and using Lee twophase model. Lee model based on CahnHilliard diffuse interface approach uses potential form of intermolecular forces and isotropic finite difference discretization. This approach is able to avoid parasitic currents and leads to a stable procedure to simulate twophase flows. Deformation and coalescence of bubbles depend on a balance between surface tension forces, gravity forces, inertia forces and viscous forces. A simulation code is developed and validated by analysis of some basic problems such as bubble relaxation, merging bubbles, merging droplets and single rising bubble. Also, the results of two rising bubbles as the simplest interaction problem of rising bubbles have been calculated and presented. As the main results, square and lozenge initial configuration of nine rising bubbles are studied at Eotvos numbers of 2, 10 and 50. Twophase flow behavior of multiple rising bubbles at same configurations is discussed and the effect of Eotvos number is also presented. Finally, velocity field of nine rising bubbles is presented and discussed with details.