Granular segregation as a critical phenomenon

TL;DR

This study investigates pattern formation in shaken granular mixtures, revealing a critical filling fraction where segregation exhibits phase transition characteristics like critical slowing down.

Contribution

It identifies a critical filling fraction in granular segregation that behaves like a second order phase transition, supported by experimental evidence.

Findings

Critical filling fraction at C=0.647±0.049

Segregation patterns show critical slowing down

Evidence of second order phase transition behavior

Abstract

We present the results of an experimental study of patterned segregation in a horizontally shaken shallow layer of a binary mixture of dry particles. An order parameter for the segregated structures is defined and the effect of the variation of the combined filling fraction, $C$, of the mixture on the observed pattern formation is systematically studied. The surprising result is that there is a critical event associated with the onset of the pattern, at $C=0.647\pm0.049$, which has the characteristics of a second order phase transition, including critical slowing down.