A coupled particle dynamics-lattice Boltzmann method model for particle-resolved direct numerical simulation of gas–liquid–solid flow with an irregular particle expressed by multi-sphere algorithm

In this paper, we develop a lattice Boltzmann (LB) model for simulating the gas–liquid–solid three-phase flow. Based on the gas–solid two-phase fluid model in the framework of the lattice Boltzmann method (LBM), a multiphase fluid–solid two-way coupling algorithm is proposed. In this model, the fluid–fluid interface is tracked using a phase-field method. Kinetic-theory-based boundary treatment, such as the interpolated bounce back, combined with the momentum exchange methods handle flow–particle interactions. Particle dynamics (PD) equation depicts the particle's movement and direction. Multi-sphere algorithm is inserted into the LBM frame to efficiently express the irregular particle borrowing from the idea of multi-sphere model in a discrete element method frame. Several typical benchmark cases are used to validate the present model, including the flow around the static and rotating cylinder, the wetting behavior of regular and irregular particles on the liquid–gas interface, the setting of a cylindrical particle, and regular and irregular particles sinking into and pulled out water. The numerical results show that the model agrees well with analytical solutions, experimental data, and published literature. The coupled PD-LBM model is validated and can accurately simulate any gas–liquid–solid three-phase flow system containing moving contact line phenomena.