Silo Music and Silo Quake: Granular Flow Induced Vibration

TL;DR

This study demonstrates that silo music results from resonance caused by silo quake, which is driven by stick-slip friction between granular material and silo walls, with flow pulsations influenced by surface properties.

Contribution

It reveals that silo quake is caused by frictional stick-slip motion and does not depend on resonance, clarifying the mechanisms behind silo music and vibrations.

Findings

Silo music is a resonance phenomenon linked to silo quake.

Flow pulsations depend on surface properties of materials.

Silo quake is driven by stick-slip friction, not resonance.

Abstract

Acceleration and sound measurements during granular discharge from silos are used to show that silo music is a sound resonance produced by silo quake. The latter is produced by stick-slip friction between the wall and the granular material in tall narrow silos. For the discharge rates studied, the occurrence and frequency of flow pulsations are determined primarily by the surface properties of the granular material and the silo wall. The measurements show that the pulsating motion of the granular material drives the oscillatory motion of the silo and the occurrence of silo quake does not require a resonant interaction between the silo and the granular material.