Dynamic Simulation of the Packing of Ellipsoidal Particles

Abstract

This paper presents a numerical study of the packing of nonspherical particles by the use of the discrete element method. The shapes considered are oblate and prolate spheroids, with the aspect ratio varying from 0.1 to 7.0. It is shown that the predicted relationship between packing fraction and aspect ratio is consistent with those reported in the literature. Ellipsoids can pack more densely than spheres. The maximum packing fraction occurs at an aspect ratio of 0.6 for oblate spheroids, and 1.80 for prolate spheroids. The packing characteristics with aspect ratio are further analyzed in terms of structural parameters such as coordination number and radial distribution function. It is shown that ellipsoids with small or large aspect ratios tend to give a locally ordered structure. The results demonstrate that DEM provides a useful method to investigate the packing dynamics of ellipsoidal particles.

Segregation of binary mixtures of spheres and ellipsoids

“…According to Abreu et al [6], ellipsoids with aspect ratios Į = 0.1 and 10 should segregate to the top due to lower packing density than spheres in mono-dispersed systems [11]. Accordingly, ellipsoids of aspect ratios Ș = 0.5 and 2 should move downwards to the bottom of the container.…”

“…The reduced radius which is related to the shape curvature of ellipsoidal particles at contact point is also used for force calculations. More detailed information can be found in [11].…”

DEM simulation of the packing of rodlike particles

“…It should be noted that the coordination number is sensitive to the critical separation distance less than which two particles are considered to be in contact. Though different critical distance may give different results of the mean coordination number, they have the same tendency [20]. As adopted by many other authors [20,22], the cutoff separation distance is normally set to 0.01d.…”

“…Base on DEM simulation, Deng and Dave [18] studied the effect of the particle size and cohesiveness on the packing structure of spherocylinders with aspect ratio not more than 3.0, and confirmed the existence of single contact in the packing structure of fine and cohesive particles. Although DEM simulations become more and more popular for the packing of ellipsoidal particles [19,20], breakage or flow of spherocylinders [4,21], there have few studies focusing on the packing of rods with a large aspect ratio.…”

Analysis of Voronoi clusters in the packing of uniform spheres

“…In this model, different interparticle forces including the van der Waals force for fine particles, various particle-fluid interaction forces in the settling of particles in liquid, and the particle-wall interaction and in vibration are explicitly considered without the assumptions made on the packing growth as in other kinetic simulations. Hence, the generated packings are actually more related to granular matter as discussed by Zhou et al [12]. Voronoi tessellation is a widely-used method to characterize random packing [1,13].…”