Silo hiccups: Dynamic effects of dilatancy in granular flow

Abstract

The granular flow through an open silo is investigated experimentally. A mechanism based both on the dilation of the granular medium and an interaction with the interstitial gas causes the flow to stop at regular intervals. The experiments are carried out at different surrounding pressures P0, and it is found that the intermittent flow becomes continuous at sufficiently low P0, showing that the intermittency is linked to the interaction the gas. The scaling of the average flow rate with particle size further supports our view of the gas-grain interaction.