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The flow in the square cavity with internal obstacles exists widely; thus, investigating the effect of the existence of the obstacles on the flow and the motion of the solid particles is important. To understand, predict, and control the motion of the solid particles, the motion of a neutrally buoyant circular particle in a lid-driven square cavity with an internal circular obstacle is studied with the lattice Boltzmann method, where the effects of the obstacle size, obstacle location, initial position of the circular particle, and Reynolds number are investigated. Under the effect of the obstacle, the flow and the motion of the particle are quite different. Especially, under some cases, no limit cycle is observed, and the particle is captured by the secondary vortex at the lower layer of the square cavity, which is insensitive to the initial position of the circular particle. The effect of the Reynolds number on the motion of the particle is significant, with the increase in the Reynolds number, and the motion of the particle is different obviously. At low Reynolds numbers, the motion of the particle is confined by the primary vortex, which moves along the limit cycle at the upper layer of the square cavity. With the increase in the Reynolds number, the effect of the inertia of the particle becomes stronger, and the particle moves from the primary vortex to the secondary vortex until it is captured by the secondary vortex. At relatively high Reynolds numbers, the primary vortex develops, and the particle is confined by the primary vortex again, forming another limit cycle. [ABSTRACT FROM AUTHOR]

The interaction between a particle cluster and a single particle during sedimentation is studied with the lattice Boltzmann method, where the effects of the initial distance and particle number on the motion and distribution of the particle cluster are investigated. Compared to the case without the single particle, the motion and distribution of the particle cluster are affected significantly due to the effect of the single particle. Due to the interaction between the particle cluster and the single particle, the particle-particle interaction becomes stronger; compared to the case without the single particle, the velocity fluctuation of the particle cluster is much more intensive. Besides, the particle cluster is scattered by the single particle, and the distribution of the particle cluster becomes more inhomogeneous. [ABSTRACT FROM AUTHOR]