Mixing and condensation in a wet granular medium

TL;DR

This study investigates how small amounts of liquid influence the behavior and segregation of mixed glass beads, revealing a transition to viscoplasticity driven by liquid bridge forces and characterized by a phase diagram.

Contribution

It introduces a phase diagram for wet granular media, linking liquid content to segregation and viscoplastic transition, highlighting the role of hysteretic liquid bridges.

Findings

Segregation depends nontrivially on liquid content.

A critical liquid content induces a transition to viscoplastic behavior.

The transition is explained by hysteretic liquid bridge forces.

Abstract

We have studied the effect of small amounts of added liquid on the dynamic behavior of a granular system consisting of a mixture of glass beads of two different sizes. Segregation of the large beads to the top of the sample is found to depend in a nontrivial way on the liquid content. A transition to viscoplastic behavior occurs at a critical liquid content, which depends upon the bead size. We show that this transition can be interpreted as a condensation due to the hysteretic liquid bridge forces connecting the beads, and provide the corresponding phase diagram.