Uniform shape elongation effects on the random packings of uniaxially variable superellipsoids

Abstract

Uniaxially variable (rod-like) particles are common in nature and industry. However, the aspect ratio effects on the random packings for differently shaped rod-like particles are not uniform by their innate definitions of aspect ratios. In this work, we propose new definitions of effective aspect ratios that take the surface shape information into account and observe uniform shape elongation effects on the random packing densities. The packing density reaches a maximal value with the effective aspect ratio to be about 1.5. We also observe symmetric high-density regions on the packing-density map. Finally, we carry out the Voronoi analysis and find that the surface shape of particles plays a more important role in changing the local packing properties than the aspect ratio. Our work provides a uniform definition for the aspect ratio of differently shaped rod-like particles and leads to a better understanding towards the particle shape effects on random packings.