Particle Scale Dynamics in Granular Impact

TL;DR

This study investigates the microscopic grain-scale mechanisms during granular impact, revealing that acoustic activity at the intruder's leading edge influences deceleration and force fluctuations, providing new insights into granular dynamics.

Contribution

It introduces a detailed experimental analysis linking acoustic activity to force fluctuations and deceleration in granular impact, offering a microscopic perspective.

Findings

Acoustic activity fluctuates strongly at the intruder front.

Intruder deceleration correlates with acoustic fluctuations.

Average dynamics align with empirical force laws.

Abstract

We perform an experimental study of granular impact, where intruders strike 2D beds of photoelastic disks from above. High-speed video captures the intruder dynamics and the local granular force response, allowing investigation of grain-scale mechanisms in this process. We observe rich acoustic behavior at the leading edge of the intruder, strongly fluctuating in space and time, and we show that this acoustic activity controls the intruder deceleration, including large force fluctuations at short time scales. The average intruder dynamics match previous studies using empirical force laws, suggesting a new microscopic picture, where acoustic energy is carried away and dissipated.