Numerical simulation of a rising CO2 droplet in the initial accelerating stage by a multiphase lattice Boltzmann method

•A stable, efficient and accurate immiscible multi-phase lattice Boltzmann method is developed.•A domain shift scheme and an alternative re-initialization scheme are developed.•The multi-phase lattice Boltzmann method is implemented on GPU.•The proposed method is applied to predict terminal rising velocity of a CO2 droplet in seawater.

A multi-phase flow model which applies lattice Boltzmann method (LBM) is developed for numerical simulation of the initial accelerating stage of a rising CO2 droplet in the deep ocean. In the present LBM model, a multiple-relaxation time (MRT) collision operator is adopted to increase the numerical stability, and a color model is used to treat the two-phase fluid. A domain shift scheme is proposed to make the long distance calculation available. The computation is accelerated by using the GPU computing and correspondent parallel implementation techniques are developed. The proposed numerical model is first validated against several benchmark problems: Laplace law test, binary Poiseuille flow problem and rise of a toluene droplet. Then numerical simulation of a liquid CO2 droplet rising from quiescence to its steady state is carried out and the results are compared to a laboratory experiment. Excellent agreement is obtained on both terminal velocity and variation of droplet shape.