Energetics of particle-size segregation

TL;DR

This paper develops a continuum energy-based framework to analyze particle-size segregation in granular flows, revealing how energy ratios depend on the segregation Péclet number and enabling control of segregation-mixing states.

Contribution

It introduces a novel continuum framework for the energetics of granular segregation, linking energy ratios to the segregation Péclet number and demonstrating its applicability through numerical experiments.

Findings

Two distinct energetic phases identified during segregation and remixing.

The energy ratio scales as Pe^{-1/2}_{sr} in steady state.

Potential to predict and control segregation-mixing states using system parameters.

Abstract

We introduce a continuum framework for the energetics of particle-size segregation in bidisperse granular flows. Building on continuum segregation equations and a recent segregation flux model, the proposed framework offers general analytical expressions to study the physics of granular flows from a mechanical energy perspective. To demonstrate the framework's applicability, we examined the energetics in shear-driven flows. Numerical experiments with varying frictional coefficients and particle-size ratios revealed two distinct phases in the associated energetics with particle segregation and diffusive remixing, and that the potential energy to the kinetic energy ratio in the steady state follows the scaling relationship $\hat{E}^{(s)}_{gp} / \hat{E}^{(s)}_{k} \propto Pe^{-1/2}_{sr}$ for $0.4 \leq Pe_{sr} \leq 300$, the segregation-rheology P\'eclet number. Our findings hint that the bulk segregation-mixing state can be predicted and controlled using $Pe_{sr}$, determined from known system parameters, providing a impactful tool for engineering and geophysical applications.