(367g) A Modified Kinetic Theory Model Bridging Dense and Dilute Regimes of Frictional Granular Flow

We investigate the rheology of granular materials in both the dense and dilute inertial regimes via molecular dynamics simulations of homogeneous, simple shear flows of soft, frictional spheres. Though traditional kinetic theories are often used for continuum modeling of granular materials, they fail to describe flow behavior in dense systems near the jamming transition and do not account explicitly for interparticle friction. On the basis of our simulations and a recently-developed dense- regime model [1], we propose modifications to the commonly-used Garzó-Dufty kinetic theory [2], originally developed for frictionless particles at low-to-moderate solid fraction. These modifications include 1) a new expression for the radial distribution function at contact and 2) correction factors to the shear stress and energy dissipation expressions. These changes allow the new model to predict the increase in pressure in the dense regime as well as the decrease in pressure in the dilute regime that result when increasing the interparticle friction coefficient. Additionally, they enable the prediction of a yield stress in the close-packed limit, a feature not found in previous kinetic theories.

[1] S. Chialvo, J. Sun, and S. Sundaresan. Phys. Rev. E 85, 021305 (2012).
[2] V. Garzó and J.W. Dufty. Phys. Rev. E 59, 5895 (1999).