Universal and Wide Shear Zones in Granular Bulk Flow

Fenistein, Denis; Meent, Jan Willem van de; Hecke, Martin van

doi:10.1103/physrevlett.92.094301

Cited by 134 publications

(200 citation statements)

References 23 publications

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“…A particular example in which the shear band is induced through the use of appropriate boundary conditions is the split-bottom container geometry introduced in 4,5 in the form of a modified Couette cell. In this configuration the bottom of the cell is split into two disks that rotate relatively to each other, and are attached to the inner and outer cylindrical wall of the cell.…”

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confidence: 99%

Finite width of quasistatic shear bands

2008

Phys. Rev. E

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I study the average deformation rate of an amorphous material submitted to an external uniform shear strain rate, in the geometry known as the split-bottom configuration. The material is described using a stochastic model of plasticity at a mesoscopic scale. A shear band is observed to start at the split point at the bottom, and widen progressively towards the surface. In a two-dimensional geometry the average statistical properties of the shear band look similar to those of the directed polymer model. In particular, the surface width of the shear band is found to scale with the system height H as H α with α = 0.68 ± 0.02. In more realistic three dimensional simulations the exponent changes to α = 0.60 ± 0.02 and the bulk profile of the width of the shear band is closer to a quarter of circle, as it was observed to be the case in recent simulations of granular materials.

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confidence: 99%

Finite width of quasistatic shear bands

2008

Phys. Rev. E

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“…1(d)]. The transition occurs around the ratio H/R s = 0.7 [5,8,9], where two shear bands exist [ Fig. 1(c)].…”

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Hydrodynamic modeling of granular flows in a modified Couette cell

Jop

2008

Phys. Rev. E

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We present simulations of granular flows in a modified Couette cell, using a continuum model recently proposed for dense granular flows. Based on a friction coefficient, which depends on an inertial number, the model captures the positions of the wide shear bands. We show that a smooth transition in velocity-profile shape occurs when increasing the height of the granular material, leading to a differential rotation of the central part close to the surface. The numerical predictions are in qualitative agreement with previous experimental results. The model provides predictions for the increase of the shear bands width when increasing the rotation rate.

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“…These rearrangement events lead to long-range fluctuations, or agitations, that influence the behavior of nearby clusters, leading to macroscopic manifestations of cooperativity, which are quite varied. Most familiarly, the length-scales associated with velocity fields in dense granular flows depend crucially upon the grain size [1], with grain-size dependent shear band widths being observed in many geometries [2][3][4][5][6][7][8]. Other manifestations of cooperativity include the dependence of volumetric outflow rate on grain size in drainage flows [9,10] and the so-called H stop -effect, in which thin granular layers require greater tilt to flow down an inclined surface [11,12].…”

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Continuum Modeling of Secondary Rheology in Dense Granular Materials

Henann

Kamrin

2014

Phys. Rev. Lett.

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Recently, a new nonlocal granular rheology was successfully used to predict steady granular flows, including grain-size-dependent shear features, in a wide variety of flow configurations, including all variations of the split-bottom cell. A related problem in granular flow is that of mechanicallyinduced creep, in which shear deformation in one region of a granular medium fluidizes its entirety, including regions far from the sheared zone, effectively erasing the yield condition everywhere. This enables creep deformation when a force is applied in the nominally quiescent region through an intruder such as a cylindrical or spherical probe. We show that the nonlocal fluidity model is capable of capturing this phenomenology. Specifically, we explore creep of a circular intruder in a two-dimensional annular Couette cell and show that the model captures all salient features observed in experiments, including both the rate-independent nature of creep for sufficiently slow driving rates and the faster-than-linear increase in the creep speed with the force applied to the intruder.Cooperativity is a hallmark of quasi-static, dense granular deformation. At a microscopic level, deformation in granular materials takes place through the rearrangement of clusters of grains. These rearrangement events lead to long-range fluctuations, or agitations, that influence the behavior of nearby clusters, leading to macroscopic manifestations of cooperativity, which are quite varied. Most familiarly, the length-scales associated with velocity fields in dense granular flows depend crucially upon the grain size [1], with grain-size dependent shear band widths being observed in many geometries [2][3][4][5][6][7][8]. Other manifestations of cooperativity include the dependence of volumetric outflow rate on grain size in drainage flows [9,10] and the so-called H stop -effect, in which thin granular layers require greater tilt to flow down an inclined surface [11,12]. A more recently-observed example of cooperativity in dense granular flows is that of mechanicallyinduced creep [13][14][15], understood as follows. When an intruder, such as a sphere, rod, or vane, is placed in a dense granular material, one must apply a force to the intruder that exceeds a critical value in order to move it through the granular media. However, shear deformation far from the intruder enables it to move, or creep, through the granular media for any non-zero value of the applied force -even when this force is less than the critical value. That is to say, flow anywhere in a granular media erases the yield condition everywhere! These cooperative phenomena provide stringent tests for a continuum model of granular flow. Local approaches to continuum modeling of granular materials, such as granular rheology [16][17][18] or soil mechanics [19,20], which relate the stress at a point to the local strain, strain-rate, or locally evolved state variables, are not equipped to address size-dependent manifestations of cooperativity. Recently, we proposed a nonlocal rheology for ...

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Universal and Wide Shear Zones in Granular Bulk Flow

Cited by 134 publications

References 23 publications

Finite width of quasistatic shear bands

Finite width of quasistatic shear bands

Hydrodynamic modeling of granular flows in a modified Couette cell

Continuum Modeling of Secondary Rheology in Dense Granular Materials

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