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Non-local rheology of dense granular flows

Bouzid, Mehdi; Trulsson, Martin LU ; Izzet, Adrien; Favier De Coulomb, Adeline; Claudin, Philippe; Clément, Eric and Andreotti, Bruno (2017) In EPJ Web of Conferences 140.
Abstract

The rheology of dense granular flows is studied numerically in a shear cell controlled at constant pressure and shear stress, confined between two granular shear flows. We show that a liquid state can be achieved even far below the yield stress, whose flow can be described with the same rheology as above the yield stress. A non-local constitutive relation is derived from dimensional analysis through a gradient expansion and calibrated using the spatial relaxation of velocity profiles observed under homogeneous stresses. Both for frictional and frictionless grains, the relaxation length is found to diverge as the inverse square root of the distance to the yield point, on both sides of that point. We also make use of a micro-rheometer to... (More)

The rheology of dense granular flows is studied numerically in a shear cell controlled at constant pressure and shear stress, confined between two granular shear flows. We show that a liquid state can be achieved even far below the yield stress, whose flow can be described with the same rheology as above the yield stress. A non-local constitutive relation is derived from dimensional analysis through a gradient expansion and calibrated using the spatial relaxation of velocity profiles observed under homogeneous stresses. Both for frictional and frictionless grains, the relaxation length is found to diverge as the inverse square root of the distance to the yield point, on both sides of that point. We also make use of a micro-rheometer to determine the influence of a distant shear band on the local rheological behaviour. Finally, we compare various approaches based on different non-local constitutive relations and choices for the fluidity parameter. We emphasise that, to discriminate between the different approaches proposed in the literature, one has to go beyond the predictions derived from linearisation around a uniform stress profile, such as that obtained in a simple shear cell. We argue that future tests can be based on the nature of the chosen fluidity parameter, and the related boundary conditions, as well as the hypothesis made to derive the models and the dynamical mechanisms underlying their dynamics.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
EPJ Web of Conferences
volume
140
publisher
EDP Sciences
external identifiers
  • scopus:85024095748
ISSN
2101-6275
DOI
10.1051/epjconf/201714011013
language
English
LU publication?
yes
id
7025667d-248f-4069-b337-b8ce21cb5531
date added to LUP
2017-07-27 13:35:08
date last changed
2018-01-07 12:13:24
@article{7025667d-248f-4069-b337-b8ce21cb5531,
  abstract     = {<p>The rheology of dense granular flows is studied numerically in a shear cell controlled at constant pressure and shear stress, confined between two granular shear flows. We show that a liquid state can be achieved even far below the yield stress, whose flow can be described with the same rheology as above the yield stress. A non-local constitutive relation is derived from dimensional analysis through a gradient expansion and calibrated using the spatial relaxation of velocity profiles observed under homogeneous stresses. Both for frictional and frictionless grains, the relaxation length is found to diverge as the inverse square root of the distance to the yield point, on both sides of that point. We also make use of a micro-rheometer to determine the influence of a distant shear band on the local rheological behaviour. Finally, we compare various approaches based on different non-local constitutive relations and choices for the fluidity parameter. We emphasise that, to discriminate between the different approaches proposed in the literature, one has to go beyond the predictions derived from linearisation around a uniform stress profile, such as that obtained in a simple shear cell. We argue that future tests can be based on the nature of the chosen fluidity parameter, and the related boundary conditions, as well as the hypothesis made to derive the models and the dynamical mechanisms underlying their dynamics.</p>},
  articleno    = {11013},
  author       = {Bouzid, Mehdi and Trulsson, Martin and Izzet, Adrien and Favier De Coulomb, Adeline and Claudin, Philippe and Clément, Eric and Andreotti, Bruno},
  issn         = {2101-6275},
  language     = {eng},
  month        = {06},
  publisher    = {EDP Sciences},
  series       = {EPJ Web of Conferences},
  title        = {Non-local rheology of dense granular flows},
  url          = {http://dx.doi.org/10.1051/epjconf/201714011013},
  volume       = {140},
  year         = {2017},
}