Pattern formation in a fully three-dimensional segregating granular flow

Yu, Mingxin; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

doi:10.1103/physreve.99.062905

Cited by 6 publications

(2 citation statements)

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“…Consequently, the axial drift and resulting recirculation cells are buried in the noise related collisional diffusion as particles flow. Nevertheless, axial drift affects segregation pattern formation in spherical tumblers with size-bidisperse particles [22,23].…”

Section: Introductionmentioning

confidence: 99%

Recirculation cells for granular flow in cylindrical rotating tumblers

2018

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To better understand the velocity field and flowing layer structure, we have performed a detailed discrete element method study of the flow of monodisperse particles in a partially filled three-dimensional cylindrical rotating tumblers. Similar to what occurs near the poles in spherical and conical tumblers, recirculation cells (secondary flows) develop near the flat endwalls of a cylindrical tumbler in which particles near the surface drift axially toward the endwall, while particles deeper in the flowing layer drift axially toward the midlength of the tumbler. Another recirculation cell with the opposite sense develops next to each endwall recirculation cell, extending to the midlength of the tumbler. For a long enough tumbler, each endwall cell is about one quarter of the tumbler diameter in length. Endwall cells are insensitive to tumbler length and relatively insensitive to rotation speed (so long as the flowing layer remains flat and continuously flowing) or fill level (from 25% to 50% full). However, for shorter tumblers (0.5 to 1.0 length/diameter aspect ratio) the endwall cell size does not change much, while center cells reduce their size and eventually disappear for the shortest tumblers. For longer tumblers (length/diameter aspect ratio larger than 2), a stagnation zone appears in between the central cells. These results provide insight into the mixing of monodisperse particles in rotating cylindrical tumblers as well as the frictional effects of the tumbler endwalls.

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Section: Introductionmentioning

confidence: 99%

Recirculation cells for granular flow in cylindrical rotating tumblers

2018

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“…isometries have been shown to capture the underlying structure in spherical tumbler flows[Juarez et al (2012);Sturman et al (2008);Yu et al (2019)], with deviations in experimental models occurring due to the material passing through the flowing layer or diffusive-like effects from particle-particle interaction. Work has been done to understand the bifurcations that occur in the models when introducing shearing from the flowing layer into the piecewise isometry.…”

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Rates of mixing in models of fluid devices with discontinuities

Kreczak¹

2020

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The dynamics of mixing by cutting and shuffling are subtle and not well understood. We present mixing dynamics arising from fundamental models capturing the essence of discontinuous stirring with diffusion. When the stirring is governed by purely cutting and shuffling, we reveal that the time to achieve a mixed condition varies polynomially with diffusivity rate with an exponent less than unity. In stirring fields which are chaotic we observe that the addition of discontinuous transformations contaminates mixing. Long-time mixing rates behave counter-intuitively when varying the diffusivity rate and a deceleration of mixing with increasing diffusion coefficient is observed, sometimes overshooting analytically derived bounds.

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