Flow of magnetic repelling grains in a two-dimensional silo

TL;DR

This study investigates the unique discharge dynamics of a two-dimensional silo filled with magnetic grains that repel each other, revealing differences from conventional granular flow, including altered density and velocity profiles and clogging phenomena.

Contribution

It introduces the first analysis of magnetic repelling grains in silo discharge, highlighting how non-contact interactions influence flow behavior and clogging.

Findings

Flow rate follows a power-law with exponent 3/2, similar to non-repulsive systems.

Density and velocity profiles differ significantly from conventional granular flows.

Clogging occurs below a critical aperture size, despite the absence of contact forces.

Abstract

During a typical silo discharge, the material flow rate is determined by the contact forces between the grains. Here, we report an original study concerning the discharge of a two-dimensional silo filled with repelling magnetic grains. This non-contact interaction leads to a different dynamics from the one observed with conventional granular materials. We found that, although the flow rate dependence on the aperture size follows roughly the power-law with an exponent $3/2$ found in non-repulsive systems, the density and velocity profiles during the discharge are totally different. New phenomena must be taken into account. Despite the absence of contacts, clogging and intermittence were also observed for apertures smaller than a critical size determined by the effective radius of the repulsive grains.