Bridges in three-dimensional granular packings: experiments and simulations

TL;DR

This study investigates the structure and size distribution of bridges in 3D granular packings through experiments and simulations, revealing different behaviors for small and large bridges and highlighting the importance of packing fraction.

Contribution

First experimental analysis of bridge structures in 3D granular packings, validating simulation results and emphasizing packing fraction's role.

Findings

Small bridges are mostly linear with exponential size distribution.

Large bridges are complex with power-law size distribution.

Experimental results align with simulations for size and orientation distributions.

Abstract

In this letter, we present the first experimental study of bridge structures in three-dimensional dry granular packings. When bridges are small, they are predominantly 'linear', and have an exponential size distribution. Larger, predominantly 'complex' bridges, are confirmed to follow a power-law size distribution. Our experiments, which use X-ray tomography, are in good agreement with the simulations presented here, for the distribution of sizes, end-to-end lengths, base extensions and orientations of predominantly linear bridges. Quantitative differences between the present experiment and earlier simulations suggest that packing fraction is an important determinant of bridge structure.