Dynamics of driven granular suspensions

TL;DR

This paper introduces a simple, scalable model for simulating the dynamics of large-scale driven granular suspensions, focusing on fluidized beds and their response to flow changes.

Contribution

It presents a new event-driven simulation model capable of handling millions of particles and studies the interface dynamics and transient behaviors in fluidized granular beds.

Findings

Interface width is independent of packing fraction in steady state

The model can simulate large systems efficiently

Timescales for reaching steady state after flow changes are characterized

Abstract

We suggest a simple model for the dynamics of granular particles in suspension which is suitable for an event driven algorithm, allowing to simulate $N=\mathcal{O}(10^6)$ particles or more. As a first application we consider a dense granular packing which is fluidized by an upward stream of liquid, i.e. a fluidized bed. In the stationary state, when all forces balance, we always observe a well defined interface whose width is approximately independent of packing fraction. We also study the dynamics of expansion and sedimentation after a sudden change in flow rate giving rise to a change in stationary packing fraction and determine the timescale to reach a stationary state.