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Issue 25, 2018
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Size-dependence of the flow threshold in dense granular materials

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Abstract

The flow threshold in dense granular materials is typically modeled by local, stress-based criteria. However, grain-scale cooperativity leads to size effects that cannot be captured with local conditions. In a widely studied example, flows of thin layers of grains down an inclined surface exhibit a size effect whereby thinner layers require more tilt to flow. In this paper, we consider the question of whether the size-dependence of the flow threshold observed in inclined plane flow is configurationally general. Specifically, we consider three different examples of inhomogeneous flow – planar shear flow with gravity, annular shear flow, and vertical chute flow – using two-dimensional discrete-element method calculations and show that the flow threshold is indeed size-dependent in these flow configurations, displaying additional strengthening as the system size is reduced. We then show that the nonlocal granular fluidity model – a nonlocal continuum model for dense granular flow – is capable of quantitatively capturing the observed size-dependent strengthening in all three flow configurations.

Graphical abstract: Size-dependence of the flow threshold in dense granular materials

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Publication details

The article was received on 24 Apr 2018, accepted on 04 Jun 2018 and first published on 06 Jun 2018


Article type: Paper
DOI: 10.1039/C8SM00843D
Citation: Soft Matter, 2018,14, 5294-5305
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    Size-dependence of the flow threshold in dense granular materials

    D. Liu and D. L. Henann, Soft Matter, 2018, 14, 5294
    DOI: 10.1039/C8SM00843D

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