Simulating the interactions of two freely settling spherical particles in Newtonian fluid using lattice-Boltzmann method

摘要

The interactions of two freely settling spherical particles in a three dimensional channel are investigated employing the lattice-Boltzmann method with discrete external boundary force (LBM-EBF). By changing the initial separation distance and relative angle between the two particles, a comprehensive analysis about the impact of various parameters on the dynamics of the particle motion and particle–particle interactions is made. The terminal Reynolds numbers based on the diameter of particle and the terminal vertical velocity is about O(100). Three different regimes are identified in the two particles settling system: repulsion, attraction and transition regime. Each regime depends on the initial separation distance and the relative angle of the two particles. The general trend is that the smaller the initial angle, the more likely interaction between them is repulsion. On the contrary, the larger the initial angle, the more likely interaction is attraction. Further, the translation and the rotation of the particles as well as the long-body particle pair behavior and some flow patterns are systematically investigated.