Forced Granular Orifice Flow

TL;DR

This study experimentally demonstrates that the flow rate of granular material through an orifice increases linearly with applied force, challenging previous assumptions and attributing the behavior to energy dissipation within the material.

Contribution

It reveals a novel linear relationship between force and flow rate in granular orifice flow, supported by energy balance analysis, contrasting with traditional views of force screening.

Findings

Flow rate increases linearly with applied force

Dissipation in granular material explains the behavior

Contradicts traditional view of force screening

Abstract

The flow of granular material through an orifice is studied experimentally as a function of force $F$ pushing the flow. It is found that the flow rate increases linearly with $F$ -- a new, unexpected result that is in contrast to the usual view that $F$, completely screened by an arch formed around the orifice, has no way of altering the rate. Employing energy balance, we show that this behavior results mainly from dissipation in the granular material.