Issue |
EPL
Volume 84, Number 6, December 2008
|
|
---|---|---|
Article Number | 64003 | |
Number of page(s) | 6 | |
Section | Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics | |
DOI | https://doi.org/10.1209/0295-5075/84/64003 | |
Published online | 12 January 2009 |
Fast decay of the velocity autocorrelation function in dense shear flow of inelastic hard spheres
1
Department of Physics, Clark University - Worcester, MA 01610, USA
2
Department of Chemical Engineering, Indian Institute of Science - Bangalore 560012 India
Corresponding author: akudrolli@clarku.edu
Received:
26
September
2008
Accepted:
18
November
2008
We find in complementary experiments and event-driven simulations
of sheared inelastic hard spheres that the velocity autocorrelation function
decays much faster than
obtained for a fluid
of elastic spheres at equilibrium. Particle displacements are measured in experiments inside
a gravity-driven flow sheared by a rough wall. The average packing fraction obtained in the
experiments is 0.59, and the packing fraction in the simulations is varied between 0.5 and
0.59. The motion is observed to be diffusive over long times except in experiments where
there is layering of particles parallel to boundaries, and diffusion is inhibited between
layers. Regardless, a rapid decay of
is
observed, indicating that this is a feature of the sheared dissipative fluid, and is independent
of the details of the relative particle arrangements. An important implication of our study is
that the non-analytic contribution to the shear stress may not be present in a sheared inelastic
fluid, leading to a wider range of applicability of kinetic theory approaches to dense granular
matter.
PACS: 47.57.Gc – Granular flow / 45.70.Mg – Granular flow: mixing, segregation and stratification
© EPLA, 2008
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