Experimental Study of Granular Clogging in Two-Dimensional Hopper

TL;DR

This paper experimentally investigates granular clogging in a 2D hopper, revealing that stable chain structures form arches causing clogs, and presents a model explaining clogging probability based on chain stability.

Contribution

It introduces a physical mechanism based on chain structures and a model predicting clogging probability, advancing understanding of microscopic clogging processes.

Findings

Chain structures follow a modified random walk.

Clogging occurs when chains are mechanically stable.

The model explains clogging probability with chain stability.

Abstract

We experimentally investigate the clogging process of granular materials in a two-dimensional hopper, and present a self-consistent physical mechanism of clogging based on preformed dynamic chain structures in the flow. We found that these chain structures follow a specific modified restricted random walk, and clogging occurs when they are mechanically stable enough to withstand the flow fluctuations, resulting in the formation of an arch at the outlet. We introduce a simple model which can explain the clogging probability by incorporating an analytical expression for chain formation and its transition into an arch. Our results provide insight into the microscopic mechanism of clogging in hopper flow.