Jamming of frictional spheres and random loose packing

TL;DR

This study uses simulations to explore how the friction coefficient influences the jamming transition and packing properties of disordered sphere packings, revealing universal scaling laws and the impact of friction on packing density and coordination.

Contribution

It provides new insights into the friction-dependent jamming transition, including the variation of packing fraction and coordination number, and reports universal power law scalings.

Findings

Packing fraction at jamming decreases with friction.

Coordination number at jamming decreases with friction.

Universal power law scaling observed in pressure and coordination near jamming.

Abstract

The role of friction coefficient, $\mu$, on the jamming properties of disordered, particle packings is studied using computer simulations. Compressed, soft-sphere packings are brought towards the jamming transition - the point where a packing loses mechanical stability - by decreasing the packing fraction. The values of the packing fraction at the jamming transition, $\phi^{\mu}_{c}$, gradually decrease from the random close packing point for zero friction, to a value coincident with random loose packing as the friction coefficient is increased over several orders of magnitude. This is accompanied by a decrease in the coordination number at the jamming transition, $z^{\mu}_{c}$, which varies from approximately six to four with increasing friction. Universal power law scaling is observed in the pressure and coordination number as a function of distance from the generalised, friction-dependent jamming point. Various power laws are also reported between the $\phi^{\mu}_{\rm c}$, $z^{\mu}_{\rm c}$, and $\mu$. Dependence on preparation history of the packings is also investigated.