Unifying size-topology relations in random packings of dry adhesive polydisperse spheres

TL;DR

This study investigates the size-topology relationships in random packings of dry adhesive polydisperse spheres, revealing consistent neighbor number dependence and adhesion effects, supported by a modified geometrical model.

Contribution

It introduces a modified granocentric model that accounts for adhesion effects, unifying size-topology relations in polydisperse sphere packings.

Findings

Neighbor number depends quasilinearly on particle size, regardless of distribution.

Local packing fraction varies with particle size and adhesion strength.

Adhesion influences local topology, leading to a unified description across systems.

Abstract

We study the size-topology relations in random packings of dry adhesive polydisperse microspheres with Gaussian and lognormal size distributions through a geometric tessellation. We find that the dependence of the neighbour number on the centric particle size is always quasilinear, independent of the size distribution, the size span or interparticle adhesion. The average local packing fraction as a function of normalized particle size for different size variances is well regressed on the same profile, which grows to larger values as the relative strength of adhesion decreases. As for the local coordination number-particle size profiles, they converge onto a single curve for all the adhesive particles, but will gradually transfer to another branch for non-adhesive particles. Such adhesion induced size-topology relations are interpreted theoretically by a modified geometrical "granocentric" model, where the model parameters are dependent on a dimensionless adhesion number. Our findings, together with the modified theory, provide a more unified perspective on the substantial geometry of amorphous polydisperse systems, especially those with fairly loose structures.