Vibration-induced granular segregation: a phenomenon driven by three mechanisms

TL;DR

This paper investigates how vertical vibrations cause granular segregation through three mechanisms, revealing the dominance of inertia, convection, and fluidization at different frequencies and conditions.

Contribution

It systematically analyzes the roles of inertia, convection, and fluidization in vibration-induced segregation, providing new insights into the mechanisms involved.

Findings

Inertia and convection dominate at low frequencies.

Fluidization causes buoyancy or sinkage at high frequencies.

Segregation mechanisms depend on vibration frequency and particle properties.

Abstract

The segregation of large spheres in a granular bed under vertical vibrations is studied. In our experiments we systematically measure rise times as a function of density, diameter and depth; for two different sinusoidal excitations. The measurements reveal that: at low frequencies, inertia and convection are the only mechanisms behind segregation. Inertia (convection) dominates when the relative density is greater (less) than one. At high frequencies, where convection is suppressed, fluidization of the granular bed causes either buoyancy or sinkage and segregation occurs.