Unjamming in a 3D Granular System: The Micromechanical Role of Friction in Force Distributions and Rheological Properties

TL;DR

This study uses DEM simulations to analyze how friction influences force distributions and rheological properties during unjamming in a 3D granular system of spheres.

Contribution

It provides new insights into the micromechanical role of friction in unjamming transitions and force distributions in 3D granular materials.

Findings

Friction affects structural and mechanical observables during unjamming.

Trends observed are consistent with dense granular system behaviors.

Friction-dependent relationships are identified in force and packing properties.

Abstract

In this work, we investigate the unjamming transition in a three-dimensional granular system composed of frictional spheres, in which the packing fraction is systematically reduced by random particle extractions. Using Discrete Element Method (DEM) simulations, we analyze the evolution of key micro-mechanical quantities, such as the interparticle forces, the coordination number and the overall packing density as a function of the interparticle friction coefficient. Our results reveal friction-dependent relationships on structural as well as mechanical observables, and exhibit trends that are qualitatively consistent with observations reported in dense granular systems. These trends persist despite the very different driving mechanism considered here. This paper is part of the thematic issue \emph{``Sand, silos and asteroids: clustering challenges in granular materials research''}.