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Different shear regimes in the dense granular flow in a vertical channel

Debnath, B and Kesava Rao, K and Kumaran, V (2022) Different shear regimes in the dense granular flow in a vertical channel. In: Journal of Fluid Mechanics, 945 .

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Official URL: https://doi.org/10.1017/jfm.2022.482


The steady dense granular flow in a vertical channel bounded by flat frictional walls in one horizontal direction and with periodic boundary conditions in the other horizontal and vertical directions is studied using the discrete element method. The shape of the scaled velocity profile is characterized quantitatively by a universal exponential function, and the ratio of the maximum and slip velocities is independent of the average volume fraction and the channel width. For sufficiently wide channels, the maximum and slip velocities increase proportional to, and the thickness of the shearing zones increases proportional to. There are four zones in the flow, each with distinct dynamical properties. There is no shear in the plug zone at the centre, but there is particle agitation, and the volume fraction is lower than the random close packing volume fraction. In the adjoining dense shearing zone, is greater than the volume fraction for arrested dynamics, and the granular temperature and shear rate depend on the particle stiffness. Adjacent to the dense shearing zone is the loose shearing zone where <!CDATAφ. Here, the properties do not depend on the particle stiffness, and the constitutive relations are well described by hard-particle models. The rheology in the loose shearing zone is similar to the dense flow down an inclined plane. There is high shear and a sharp decrease in in the wall shearing zone of thickness about two particle diameters, where the particle angular velocity is different from the material rotation rate due to the presence of the wall. ©

Item Type: Journal Article
Publication: Journal of Fluid Mechanics
Publisher: Cambridge University Press
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Angular velocity; Confined flow; Exponential functions; Particles (particulate matter); Rotation rate; Shear flow; Shearing; Stiffness; Volume fraction, 'Dry' ; Dense granular flows; Discrete elements method; Dry granular material; Maximum velocity; Periodic boundary conditions; Slip velocity; Velocity profiles; Vertical channels; Vertical direction, Granular materials
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Date Deposited: 30 Aug 2022 05:25
Last Modified: 30 Aug 2022 05:25
URI: https://eprints.iisc.ac.in/id/eprint/76266

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