Macroscopic friction of dry granular materials

Cruz, Frédéric da; Chevoir, François; Roux, J-N.; Iordanoff, Ivan

doi:10.1016/s0167-8922(03)80034-2

Cited by 22 publications

(23 citation statements)

References 21 publications

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“…We notice that those profiles obtained for controlled pressure are in agreement with the one measured at fixed volume [50].…”

Section: Solid Fraction and Velocitysupporting

confidence: 87%

“…The situation (I ≥ 0.1, µ = 0 and e = 0.9) corresponds to the dense limit of the kinetic theory, with binary quasielastic collisions (then the average contact time tends to the collision time [50]). In this dense limit, the Eqs.…”

Section: Collisional Limitmentioning

confidence: 99%

“…function of y. Those velocity fluctuations are uniform at the center of the sheared layer, but increase near the wall [26,50]. According to various models, this agitation of the granular material near the rough walls is responsible for the increase of the shear rate (observed in Fig.…”

Section: B Velocity Fluctuationsmentioning

confidence: 99%

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Rheophysics of dense granular materials: Discrete simulation of plane shear flows

Cruz

Emam²,

Prochnow³

et al. 2005

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We study the steady plane shear flow of a dense assembly of frictional, inelastic disks using discrete simulation and prescribing the pressure and the shear rate. We show that, in the limit of rigid grains, the shear state is determined by a single dimensionless number, called inertial number I, which describes the ratio of inertial to pressure forces. Small values of I correspond to the quasistatic regime of soil mechanics, while large values of I correspond to the collisional regime of the kinetic theory. Those shear states are homogeneous, and become intermittent in the quasi-static regime. When I increases in the intermediate regime, we measure an approximately linear decrease of the solid fraction from the maximum packing value, and an approximately linear increase of the effective friction coefficient from the static internal friction value. From those dilatancy and friction laws, we deduce the constitutive law for dense granular flows, with a plastic Coulomb term and a viscous Bagnold term. We also show that the relative velocity fluctuations follow a scaling law as a function of I. The mechanical characteristics of the grains (restitution, friction and elasticity) have a very small influence in this intermediate regime. Then, we explain how the friction law is related to the angular distribution of contact forces, and why the local frictional forces have a small contribution to the macroscopic friction. At the end, as an example of heterogeneous stress distribution, we describe the shear localization when gravity is added.

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“…We notice that those profiles obtained for controlled pressure are in agreement with the one measured at fixed volume [50].…”

Section: Solid Fraction and Velocitysupporting

confidence: 87%

Section: Collisional Limitmentioning

confidence: 99%

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Rheophysics of dense granular materials: Discrete simulation of plane shear flows

Cruz

Emam²,

Prochnow³

et al. 2005

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“…Using the plateau value of l obtained in the bulk of the flow, we can reconstruct the Bagnold profile according to eqs. (24) and (31). These profiles are plotted on figure 5i.…”

Section: Towards a Non Local Rheologymentioning

confidence: 99%

On dense granular flows

Midi¹

2004

Eur. Phys. J. E

1,642

462

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Abstract. The behaviour of dense assemblies of dry grains submitted to continuous shear deformation has been the subject of many experiments and discrete particle simulations. This paper is a collective work carried out among the French research group GDR Milieux Divisés. It proceeds from the collection of results on steady uniform granular flows obtained by different groups in six different geometries both in experiments and numerical works. The goal is to achieve a coherent presentation of the relevant quantities to be measured i.e. flowing thresholds, kinematic profiles, effective friction, etc. First, a quantitative comparison between data coming from different experiments in the same geometry enforces the robust features in each case. Second, a transversal analysis of the data across the different configurations, allows us to identify the relevant dimensionless parameters, the different flow regimes and to propose simple interpretations. The present work, more than a simple juxtaposition of results, underlines the richness of granular flows and enhances the open problem of defining a single rheology.

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“…It is possible that this could be caused by friction between the particles and the glass plate, however, through an analysis of the momentum balance for a set of tests with different shear rates and with strong support from Ref. [13,1] -numerical studies in which similar S-shaped velocity profiles were obtained in the absence base friction -we can effectively rule out friction as the reason for the shape of the shear rates in these experiments 1 . Instead, we draw from the concept of Eddy viscosity in turbulent boundary layers to formulate a simple nonlocal model by introducing an additional viscous term to the constitutive law which is limited by the distance to the wall H − |y|, such that:…”

Section: Measurementsmentioning

confidence: 56%