DEM simulation of the packing of cylindrical particles

Discrete element method is used to study the effect of particle aspect ratio on the packing structure of cylinders in this work. Two contact scenarios are complemented to detect particle contacts, following the work of Kodam et al. (Chem Eng Sci 65:5852-5862, 2010) and Guo et al. (Powder Technol 228:193-198, 2012). The results show that the packing density-aspect ratio curve has two small peaks at aspect ratio of 0.625 and 1.25, and a small cusp at aspect ratio of 1.0. Excluded volume is used to explain the variation of packing density with aspect ratio for cylinders, spherocylinders and ellipsoids. The lowest ensemble-averaged coordination number is found at aspect ratio of around 0.75. For platy cylinders, the dominant contact scenario is the face-edge contacts, followed by band-edge contacts. For elongated cylinders, the major contact scenarios are band-edge and band-band contacts. The existence of the planar faces of a platy cylinder makes the radial distribution functions of disks quite different from that of smooth-curved oblates. Most platy cylinders have their principal axis of pointing to and almost paralleling to the vertical direction, while the principal axis of elongated cylinders tends to point to the horizontal plane. The platy particles tend to form stacks composed of 2-4 particles for different aspect ratios. The force gradient increases and force magnitude becomes less uniform when L/D deviates from 1.0.