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arXiv · 1510.05718

Optimizing Packing Fraction in Granular Media Composed of Overlapping Spheres

Leah K. Roth·Heinrich M. Jaeger
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Abstract

What particle shape will generate the highest packing fraction when randomly poured into a container? In order to explore and navigate the enormous search space efficiently, we pair molecular dynamics simulations with artificial evolution. Arbitrary particle shape is represented by a set of overlapping spheres of varying diameter, enabling us to approximate smooth surfaces with a resolution proportional to the number of spheres included. We discover a family of planar triangular particles, whose packing fraction of $ϕ\sim$ 0.73 outpaces almost all reported experimental results for random packings of frictionless particles. We investigate how $ϕ$ depends on the arrangement of spheres comprising an individual particle and on the smoothness of the surface. We validate the simulations with experiments using 3D-printed copies of the simplest member of the family, a planar particle consisting of three overlapping spheres with identical radius. Direct experimental comparison with 3D-printed aspherical ellipsoids demonstrates that the triangular particles pack exceedingly well not only in the limit of large system size but also when confined to small containers.

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Leah K. Roth, Heinrich M. Jaeger. 2015-10-19. Optimizing Packing Fraction in Granular Media Composed of Overlapping Spheres. https://arxiv.org/abs/1510.05718

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