Effect of an electric field on an intermittent granular flow

TL;DR

This study investigates how applying a perpendicular electric field influences granular flow in a silo, revealing a transition from funnel to rathole flow and increased intermittency due to electric cohesion effects.

Contribution

It demonstrates that electric fields can induce a probabilistic transition in granular flow regimes and increase intermittent flow occurrences, expanding understanding of electric influence on granular dynamics.

Findings

Flow type transitions from funnel to rathole with electric field

Outlet mass flow remains unaffected by voltage

Electric field increases intermittent flow probability

Abstract

Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A DC high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow has been measured. An image subtraction technique has been applied to visualize the flow geometry and a spatiotemporal analysis of the flow dynamics has been performed. The outlet mass flow is independent of voltage, but a transition from funnel flow to rathole flow is observed. This transition is of probabilistic nature and an intermediate situation exists between the funnel and the rathole situations. At a given voltage, two kinds of flow dynamics can occur : a continuous flow or an intermittent flow. The electric field increases the probability to observe an intermittent flow.