Flux through a hole from a shaken granular medium

TL;DR

This study investigates how the flux of grains through a hole in a shaken container depends on vibration parameters, revealing a peak velocity control and a regime of density independence at high velocities.

Contribution

It demonstrates that the flux is primarily governed by the peak velocity of shaking, introducing a simple model and identifying a density-independent regime at high velocities.

Findings

Flux depends on peak velocity vmax, not on frequency or amplitude.

Flux decreases with increasing vmax and plateaus at high vmax.

A simple model explains flux behavior at low vmax.

Abstract

We have measured the flux of grains from a hole in the bottom of a shaken container of grains. We find that the peak velocity of the vibration, vmax, controls the flux, i.e., the flux is nearly independent of the frequency and acceleration amplitude for a given value of vmax. The flux decreases with increasing peak velocity and then becomes almost constant for the largest values of vmax. The data at low peak velocity can be quantitatively described by a simple model, but the crossover to nearly constant flux at larger peak velocity suggests a regime in which the granular density near the container bottom is independent of the energy input to the system.