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arXiv · 1808.01871

Shear-induced diffusion in non-local granular flows

Prashidha Kharel·Pierre Rognon
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Abstract

We investigate the properties of self-diffusion in heterogeneous dense granular flows involving a gradient of stress and inertial number. The study is based on simulated plane shear with gravity and Poiseuille flows, in which non-local effects induce some creep flow in zones where stresses are below the yield. Results show that shear-induced diffusion is qualitatively different in zones above and below the yield. Below the yield, diffusivity is no longer governed by velocity fluctuations, and we evidenced a direct scaling between diffusivity and local shear rate. This is interpreted by analysing the grain trajectories, which exhibit a caging dynamics developing in zones below the yield. We finally introduce an explicit scaling for the profile of local inertial number in these zones, which leads to a straightforward expression of the diffusivity as a function of the stress and position in non-local flows.

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Prashidha Kharel, Pierre Rognon. 2018-08-06. Shear-induced diffusion in non-local granular flows. https://doi.org/10.1209/0295-5075/124/24002

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