General features of granular Couette flow and intruder dynamics

Document Type

Article

Publication Date

6-22-2005

Abstract

This paper reports on the behaviour of uniform granular particles of diameter d undergoing a gravity-free shear flow induced through parallel bumpy boundaries that move in opposite directions at constant velocity U. Non-equilibrium, discrete simulations are performed, in which particles are modelled as inelastic, frictional spheres. The flow is described using steady state profiles of mean velocity, granular temperature, solids fraction and normal pressure. A non-uniform local shear rate, characterized by an S-shaped mean velocity profile, produces an imbalance in the contact distribution of particles in the vicinity of the walls so that they drift toward the geometric centre of the flow. A spectral analysis of the transverse velocity provides evidence of convective cell structures in the secondary velocity field whose wavelength decreases with the effective shear rate. A typical tracer particle, whose trajectory has a power spectrum suggestive of persistent fractional Brownian motion, continually samples the entire shear region. In contrast, a large intruder , which also migrates away from energetic regions adjacent to the walls, eventually becomes trapped near the mid-plane of the flow with a speed that increases with φ and the effective shear rate . Fluctuations in the evolution of its transverse velocity component obey a power law of the form Vyrms = Cφ-a, which is a consequence of its greater inertia, while fluctuations in its net force vary directly with φ. © 2005 IOP Publishing Ltd.

Identifier

21044437053 (Scopus)

Publication Title

Journal of Physics Condensed Matter

External Full Text Location

https://doi.org/10.1088/0953-8984/17/24/016

ISSN

09538984

First Page

S2609

Last Page

S2622

Issue

24

Volume

17

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