Velocity correlations in dense granular shear flows: Effects on energy dissipation and normal stress

Namiko Mitarai and Hiizu Nakanishi
Phys. Rev. E 75, 031305 – Published 26 March 2007

Abstract

We study the effect of precollisional velocity correlations on granular shear flow by molecular dynamics simulations of an inelastic hard sphere system. Comparison of the simulations with kinetic theory reveals that the theory overestimates both the energy dissipation rate and the normal stress in the dense flow region. We find that the relative normal velocity of colliding particles is smaller than that expected from random collisions, and the discrepancies in the dissipation and the normal stress can be adjusted by introducing the idea of the collisional temperature, from which we conclude that the velocity correlation neglected in the kinetic theory is responsible for the discrepancies. Our analysis of the distributions of the precollisional velocity suggests that the correlation grows through multiple inelastic collisions during the time scale of the inverse of the shear rate. As for the shear stress, the discrepancy is also found in the dense region, but it depends strongly on the particle inelasticity.

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  • Received 15 November 2006

DOI:https://doi.org/10.1103/PhysRevE.75.031305

©2007 American Physical Society

Authors & Affiliations

Namiko Mitarai1,2 and Hiizu Nakanishi1

  • 1Department of Physics, Kyushu University 33, Fukuoka 812-8581, Japan*
  • 2Niels Bohr Institute, Bledamsvej 17, DK-2100, Copenhagen, Denmark

  • *Permanent address.

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Vol. 75, Iss. 3 — March 2007

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