Void statistics and compactivity measurement in an experimental granular pile

TL;DR

This study experimentally analyzes free volume statistics in bidimensional granular packings, revealing nonextensive scaling behavior and implications for measuring Edwards' compactivity.

Contribution

It introduces a novel analysis of free volume distributions in granular media, highlighting nonextensive scaling and providing insights into the measurement of compactivity.

Findings

Logarithm of free volume distribution scales nonextensively with cluster size

Two intensive parameters can be extracted from the distribution

Nonextensivity affects the measurement of Edwards' compactivity

Abstract

We investigate experimentally the statistics of the free volume inside bidimensional granular packings, for two different kinds of grains and two levels of compaction. With the aim to gain new insight into the statistical description of granular media, we measure the free volume distribution in clusters of increasing size. Our main result is that the logarithm of the free volume distribution scales in a nonextensive way with the cluster size, while still enabling the extraction of two intensive parameters. We discuss the interpretation of these parameters, and the consequences of the nonextensivity on the possible measurements of Edwards' ''compactivity''.