Stress partition and microstructure in size-segregating granular flows

L. Staron and J. C. Phillips
Phys. Rev. E 92, 022210 – Published 25 August 2015

Abstract

When a granular mixture involving grains of different sizes is shaken, sheared, mixed, or left to flow, grains tend to separate by sizes in a process known as size segregation. In this study, we explore the size segregation mechanism in granular chute flows in terms of the pressure distribution and granular microstructure. Therefore, two-dimensional discrete numerical simulations of bidisperse granular chute flows are systematically analyzed. Based on the theoretical models of J. M. N. T. Gray and A. R. Thornton [Proc. R. Soc. A 461, 1447 (2005)] and K. M. Hill and D. S. Tan [J. Fluid Mech. 756, 54 (2014)], we explore the stress partition in the phases of small and large grains, discriminating between contact stresses and kinetic stresses. Our results support both gravity-induced and shear-gradient-induced segregation mechanisms. However, we show that the contact stress partition is extremely sensitive to the definition of the partial stress tensors and, more specifically, to the way mixed contacts (i.e., involving a small grain and a large grain) are handled, making conclusions on gravity-induced segregation uncertain. By contrast, the computation of the partial kinetic stress tensors is robust. The kinetic pressure partition exhibits a deviation from continuum mixture theory of a significantly higher amplitude than the contact pressure and displays a clear dependence on the flow dynamics. Finally, using a simple approximation for the contact partial stress tensors, we investigate how the contact stress partition relates to the flow microstructure and suggest that the latter may provide an interesting proxy for studying gravity-induced segregation.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 21 January 2015
  • Revised 29 April 2015

DOI:https://doi.org/10.1103/PhysRevE.92.022210

©2015 American Physical Society

Authors & Affiliations

L. Staron1,2,3,* and J. C. Phillips3

  • 1Sorbonne Université, UPMC Université Paris 06, UMR 7190, Institut Jean Le Rond d'Alembert, F-75005 Paris, France
  • 2CNRS, UMR 7190, Institut Jean Le Rond d'Alembert, F-75005 Paris, France
  • 3School of Earth Sciences, University of Bristol, Bristol BS8 1TH, United Kingdom

  • *lydie.staron@upmc.fr

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 92, Iss. 2 — August 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review E

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×