Transient size segregation of binary granular mixtures

TL;DR

This paper models the transient size segregation in binary granular flows over a chute using DEM simulations and a particle force-based model, predicting concentration evolution for various initial configurations and size ratios.

Contribution

It extends a particle force-based segregation model to predict time-dependent segregation in granular flows, incorporating rheology and initial condition effects.

Findings

Model accurately predicts concentration evolution for small size ratios.

Deviations occur at larger size ratios, indicating model limitations.

Initial configuration significantly affects transient segregation behavior.

Abstract

Transient size segregation of a bi-disperse granular mixture flowing over a periodic chute is studied using DEM simulations and theory. A recently developed particle force-based size segregation model has been shown to successfully predict the steady state behavior of binary granular mixtures [1]. This promising model is used to predict the time-dependent segregation of different size binary mixtures in this work. A one dimensional continuum model is developed to solve the convection-diffusion equation by incorporating a mixture segregation model along with rheological model. The inter-coupling of segregation with rheology is accounted to predict evolution of species concentration. We also investigate the effect of different initial configurations (Large near base (LNB), Small near base (SNB) and well-mixed) on the transient evolution of the flow and segregation. The particle force-based segregation model is able to predict the evolution of the concentration profile for all three initial configurations for smallest size ratio of 1.25. Significant deviations, however, are observable for larger size ratios, suggesting the need to account for the evolution of the velocity field in the model.