Study of drafting, kissing and tumbling process of two particles with different sizes using immersed boundary method in a confined medium

摘要

This paper numerically demonstrates the drafting, kissing, tumbling (DKT) phenomenon between two interacting circular, impermeable particles of different sizes in a confined medium for different scenarios using Immersed Boundary (IB) method in 2D. Two cases were considered for this particular problem. In the first case, referred to as Case 1, the trailing particle was larger in size than the leading particle and in Case 2, it was the other way round. The main emphasis of this paper was to investigate the effect of diameter ratio, γ, of the two particles, on the dynamics of the two sedimenting particles. In Case 1, it was observed that upon increasing γ from unity onwards, the particles underwent from repeated to one cycle of DKT. In Case 2, the impact of γ was more prominent. For γ ＜ 2, the particles underwent two cycles of DKT process. For γ ≥ 2 the particles first parted away from each other, but then quickly started drafting towards each other. Subsequently, after one cycle of DKT, they permanently parted away from each other. This paper also investigated the effect of initial vertical distance between the two sedimenting particles. The results presented in here are in good agreement with other published articles on similar problems.