Dynamics and stress in gravity driven granular flow

TL;DR

This paper investigates the microscopic dynamics and stress distribution in gravity-driven granular flow using simulations, revealing correlated grain motions, collision-based stress transfer, and slow local rearrangements in a steady-state dry sand system.

Contribution

It provides new insights into the microscopic collision dynamics and stress transfer mechanisms in gravity-driven granular flow, highlighting the role of collision bias and correlated motions.

Findings

Grains exhibit a power-law distribution of collision distances and times.

Stress is primarily transferred through collisions with biased directional distribution.

System shows large velocity fluctuations with correlated behavior and slow local rearrangements.

Abstract

We study, using simulations, the steady-state flow of dry sand driven by gravity in two-dimensions. An investigation of the microscopic grain dynamics reveals that grains remain separated but with a power-law distribution of distances and times between collisions. While there are large random grain velocities, many of these fluctuations are correlated across the system and local rearrangements are very slow. Stresses in the system are almost entirely transfered by collisions and the structure of the stress tensor comes almost entirely from a bias in the directions in which collisions occur.