Research On Sedimentation Of Non-spherical Particles

Particulate flows are commonly encountered in various natural phenomena and industrial processes, such as the motion of sand in the river and reservoir, the sandstorm in the nature, as well as the transportation of solid particles and gas in the pipeline. The sedimentation of particles is one of the particulate flows. Research on sedimentation of particles began as early as in the middle of the 20^th century. Direct numerical simulation (DNS) method is one of the important methods for the particulate flows. 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 simply introduced, and the DLM/FD method was used to simulate the sedimentations of a single dumbbell-like particle and a single ellipsoid particle in a vertical channel. The behaviors of sedimentation of a single dumbbell-likep particle in different Reynolds numbers and in the different initial conditions were both included in the research. The behaviors of sedimentation of a single ellipsoid particle in different conditions were involved in the consideration. In order to validate the DLM/FD method, the results of DNS method were compared with experimental results in this paper. In the end, the rules of the sedimentation of the particles were given.