A novel lattice Boltzmann model simulating gas-liquid two-phase flow

Based on the lattice Boltzmann free-energy model, a novel model is developed to simulate the gas-liquid two-phase flow with great density ratio in the viscous field. To improve the accuracy, the transfer rate control of the particle number density between two adjacent points is added to the original model, and the differential relaxation of the collision term is considered. Also, to avoid the numerical instability problems caused by the large density ratio, the six point and nine point differential schemes are used to solve ∇ and ∇2, respectively. Different from the traditional LBM implementation process, the single-step operation is divided into two steps in the paper. Unconsidering the gravity, the bubble motion is simulated and the results are compared with those from the exited models. It shows that the newly developed model has higher accuracy and numerical stability. Also, the deformation and the vortex formation of a rising bubble under gravity and the interaction of two bubbles in the horizontal and vertical directions are simulated. In the process, the mass conservation and the volume incompressibility are verified.