Experimental Research And Dynamic Simulation Of Sphere Motion

Particulate flows are commonly encountered in various natural phenomena and industrial processes, such as in the chemical and petroleum industries, the sedimentation of particles is a way of separating particles from fluid, as well as a way separating particles with different settling speeds from each other. In last decades, a variety of direct numerical simulation (DNS) methods for the particulate flows have been developed. DNS is capable of providing both microscopic and macroscopic information of the particulate flows and consequently has become an important investigative tool for multiphase flow problems. Distributed Lagrange multiplier/fictitious domain (DLM/FD) method is a promising new DNS method for the particulate flows. The basic idea of DLM/FD method is to imagine that interior space of the solid is filled with the same fluids as outside, and the fluids inside, and on solid boundary is constrained to move at the same velocity of the solid by using a distributed Lagrange multiplier. Thus a problem on a geometrically complex domain can be extended to a larger, simpler domain, which allows a fixed structured mesh can be used for the entire computation, and eliminates the need for repeated remeshing and projection.In this paper, the DLM/FD method was introduced and a new implementation of DLM/FD method is presented by using a half-staggered finite-difference scheme for the fluid flow sub-problem. Based on the new implementation, the efficiency of DLM/FD method is improved significantly. Then the DLM/FD method was used to simulate the sedimentations of a single spherical particle and two spherical particles in a vertical channel. The sedimenting behavior including trajectory, velocity and wake was analyzed at different Reynolds numbers. The DKT interaction between two spherical particles was presented. In addition, experimental research on the sedimentation of spherical particle was also performed. The comparison shows that simulation results agree well with experimental results.