Simulation And Analysis On The Packing Of Mono-Sized Spherical Particles With The Discrete Element Method

Packing of particles is found almost everywhere in both natural and industrial processes. Spherical particles are in most case a simple and reasonable model for the particles encountered in these processes. Experimental studies have severe limitations and deficiencies in describing the dynamic processes inside the packings, and direct simulation methods such as discrete element method (DEM) are of great advantages in this regard. The thesis is, therefore, devoted to the study on the packing of mono-sized spherical particles using DEM. The main content and findings of this study are as follows:1) Simulation on the packing of mono-sized spherical particles in a cylindrical container revealed the axial and radial distribution of the packing fractions which were found to be consistent with experiments. The packing was more ordered near the wall and bottom and was nearly random in the center. Roughly, the influence of the bottom could penetrate inward to the8th layer of the packing while that of the side wall was about6layers. No significant scale effect was found for these packing properties. 2) The packing of the particles in a rectangular container under vibration was also studied. A specific frequency and amplitude of the vibration could be found for given container and particles, which give the maximum packing fraction in long term. Horizontal vibration was found to be more effective for obtaining higher packing fraction.3) Simulation on the structural evolution of initially ideal face-centered-cubic (FCC) packing demonstrated its relative stability as compared to other packing forms and vertical vibration was found to be more destructive for the packing.