Rheological Transition in Granular Media

Shojaaee, Zahra; Brendel, Lothar; Wolf, Dietrich E.

doi:10.1007/978-3-540-77074-9_73

Cited by 2 publications

(9 citation statements)

References 5 publications

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“…While we found V c1 to be independent of the system size L y [10], the other boundary of the intermediate shear regime, V c2 , is more subtle. For large enough systems it is also independent of L y .…”

Section: ¯˙ /V X (Ly/2 + At)-v X (Ly/2-at)\ 7=contrasting

confidence: 54%

“…This is the point where another "critical" velocity V c1 = 0.1 is reached. When recording a histogram of V S /V, it develops two peaks at ±1, which become narrower for decreasing velocity below V c1 (see figure 1 c)) [10]. This means that the block no longer floats freely as for intermediate velocities, but is locked to one of the walls for a long time, before it switches sides.…”

Section: Formation Of Blocksmentioning

confidence: 98%

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Rheological Transitions in Two- and Three-Dimensional Granular Media

Shojaaee¹,

Ries²,

Brendel³

et al. 2009

AIP Conference Proceedings

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The planar shearing of dense systems of bidisperse as well as polydisperse, non-cohesive, hard, round, dissipative and frictional particles is simulated in two and three dimensions using Contact Dynamics. The system is sheared by smooth, frictional walls at constant shear velocities, subject to a constant normal force. Depending on the shear velocity, the system behavior belongs to one of the three different regimes (from high to low shear velocities): a) a fluid like state with almost homogeneous shearing, b) a block like state with symmetric velocity profiles and fluidization only at the walls, c) a state of broken symmetry, where a block moves essentially with one wall while possessing a shear zone at the other. The two shear velocities separating theses regimes do not depend on the distance between the walls.

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Section: ¯˙ /V X (Ly/2 + At)-v X (Ly/2-at)\ 7=contrasting

confidence: 54%

Section: Formation Of Blocksmentioning

confidence: 98%

Rheological Transitions in Two- and Three-Dimensional Granular Media

Shojaaee¹,

Ries²,

Brendel³

et al. 2009

AIP Conference Proceedings

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“…Our system size analysis shows a discontinuous transition from regime B to regime C, at V BC ≃0.10 and a continuous transition between regimes A and B completed at V AB ≃0.50 [19][20][21]. V BC and V AB are system size independent.…”

Section: B Shear Regimes and Strain Localizationmentioning

confidence: 98%

“…6) the profiles fluctuate very strongly and the top/bottom symmetry is broken. The shear strain strongly localizes at one wall, while the rest of the system, the bulk region and the opposite wall, moves like one single solid object [19][20][21]. This is the slow shear or one-shear band regime (regime C).…”

Section: A Steady Statementioning

confidence: 99%

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Shear flow of dense granular materials near smooth walls. I. Shear localization and constitutive laws in the boundary region

et al. 2012

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We report on a numerical study of the shear flow of a simple two-dimensional model of a granular material under controlled normal stress between two parallel smooth, frictional walls, moving with opposite velocities ±V . Discrete simulations, which are carried out with the contact dynamics method in dense assemblies of disks, reveal that, unlike rough walls made of strands of particles, smooth ones can lead to shear strain localization in the boundary layer. Specifically, we observe, for decreasing V , first a fluid-like regime (A), in which the whole granular layer is sheared, with a homogeneous strain rate except near the walls; then (B) a symmetric velocity profile with a solid block in the middle and strain localized near the walls and finally (C) a state with broken symmetry in which the shear rate is confined to one boundary layer, while the bulk of the material moves together with the opposite wall. Both transitions are independent of system size and occur for specific values of V . Transient times are discussed. We show that the first transition, between regimes A and B, can be deduced from constitutive laws identified for the bulk material and the boundary layer, while the second one could be associated with an instability in the behavior of the boundary layer. The boundary zone constitutive law, however, is observed to depend on the state of the bulk material nearby.

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Rheological Transition in Granular Media

Cited by 2 publications

References 5 publications

Rheological Transitions in Two- and Three-Dimensional Granular Media

Rheological Transitions in Two- and Three-Dimensional Granular Media

Shear flow of dense granular materials near smooth walls. I. Shear localization and constitutive laws in the boundary region

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