Modeling and solution method of gas-liquid-solid three-phase flow mixing

Abstract

The mixing process of gas-liquid-solid three-phase flow is a complex multi-fluid-structure coupling dynamic problem. The relationship between the particle parameters and the physical spatial scale of the flow channel directly affects the calculation convergence. Numerical modeling and mesh processing of fluid-structure bidirectional interaction in the strong shear zone are difficult. Aiming at the above problems, a method of modeling and solving the gas-liquid-solid three-phase flow mixing is proposed. Based on the volume-of-fluid coupled with discrete-element-method model, a three-phase dynamic model considering particle motion is established. By solving the momentum equation, the bidirectional coupling of two-phase fluid and particle is realized. The user-defined function communication interface is developed independently to obtain the interaction force between fluid and particles, and a porous-interphase coupling solution is proposed to describe the trajectory of particles. Taking the mixing process of three-phase flow with strong shear for example, this method is used to study the influence of different aeration conditions on the free surface, velocity distribution and particle suspension characteristics in the physical space of the flow channel. The results show that strong shear and wall action can convert the tangential velocity of the fluid into axial and radial velocity; choosing an appropriate inflation velocity can eliminate the instability of the free surface and increasing the flow velocity of the fluid has a limited effect on the suspension of particles in some areas. The research results can provide a useful reference for studying the interaction mechanism of complex multiphase flow, and also provide technical support for the mixing production control of gas-liquid-solid three-phase particles.