Cooperative effects induced by intruders evolving through a granular medium

TL;DR

This study investigates how two intruders moving through a granular medium influence particle rearrangements, revealing a characteristic distance where their effects overlap and how correlations decay with distance.

Contribution

It introduces a method to quantify the influence range of intruders in a granular medium and shows that this range is independent of intruder size, highlighting cooperative effects.

Findings

Existence of a characteristic intruder separation distance affecting grain dynamics

Intruder size has minimal impact on the influence range

Correlation between grain movements decreases with distance from intruders

Abstract

Applying mechanical perturbations in a granular assembly may rearrange the configuration of the particles. However, the spatial propagation of an event is not related to the size of the external perturbation alone. Thus, the characteristic length scale of an event is not well defined. In this study, we trigger rearrangements by driving two intruders through a vertical two-dimensional packing of disks. The amplitude of the rearrangements of the granular assembly appearing around the two evolving intruders is related to their separating distances. We show that there exists a characteristic distance between intruders under which the dynamics of the grains above one intruder is influenced by the other. The size of the intruders has little effect on this characteristic length. Finally, we show that the correlation between the movements of the grains decreases with the distance away from the intruders over a larger length scale.