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Relationship between interparticle contact lifetimes and rheology in gravity-driven granular flows
Robert Brewster1, Leonardo E Silbert, Gary S Grest
1Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA.
Summary
Discrete element simulations reveal deviations from the Bagnold relation in granular flow. A generalized Bagnold relation is proposed to explain these findings in granular dynamics.
Area of Science:
- Physics
- Geophysics
- Materials Science
Background:
- The Bagnold constitutive relation is a cornerstone for understanding granular flow.
- Its exact validity is known only for idealized, infinitely hard particles.
Purpose of the Study:
- To investigate the validity of the Bagnold relation in gravity-driven granular flow.
- To identify deviations and their dependence on interparticle interaction parameters.
Main Methods:
- Utilizing discrete element method (DEM) simulations.
- Systematically varying parameters like elastic compliance, inelastic dissipation, friction, and cohesion.
Main Results:
- Significant deviations from Bagnold rheology were observed under specific conditions.
- A strong correlation was found between Bagnold rheology breakdown and long-time tails in contact time distributions.
Conclusions:
- The Bagnold relation requires modification for realistic granular flows.
- A generalized Bagnold relation is proposed to encompass a wider range of granular behaviors.
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