Convective Flows in Sheared Packings of Spherical Particles

Fuente: arXiv
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Autores principales: Erfanifam, Mehran, Madani, Mahnoush, Shaebani, Reza, Maleki, Maniya
Formato: Preprint
Publicado: 2025
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author Erfanifam, Mehran
Madani, Mahnoush
Shaebani, Reza
Maleki, Maniya
author_facet Erfanifam, Mehran
Madani, Mahnoush
Shaebani, Reza
Maleki, Maniya
contents Understanding how granular materials respond to shear stress remains a central challenge in soft matter physics. We report direct observations of persistent granular convection in the bulk shear zones of spherical particle packings -- a phenomenon previously associated primarily with particle shape anisotropy or boundary effects. By employing various bead-coloring techniques in a split-bottom geometry, we reveal internal flow fields within sheared granular packings. We find robust convection rolls, strikingly governed by system geometry: at low filling heights, two counter-rotating convection rolls emerge, while at higher filling heights, a single dominant convection roll forms, featuring radially outward flow at the surface. This transition is driven by the height-dependent broadening of the shear zone, which introduces shear rate asymmetry across its flanks. Notably, the transition occurs entirely within the open shear band regime. These findings underscore the pivotal role of system geometry in shaping secondary flow formation in dense packings of frictional particles, suggesting possible broader relevance to geophysical flow dynamics and industrial applications.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23836
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Convective Flows in Sheared Packings of Spherical Particles
Erfanifam, Mehran
Madani, Mahnoush
Shaebani, Reza
Maleki, Maniya
Soft Condensed Matter
Understanding how granular materials respond to shear stress remains a central challenge in soft matter physics. We report direct observations of persistent granular convection in the bulk shear zones of spherical particle packings -- a phenomenon previously associated primarily with particle shape anisotropy or boundary effects. By employing various bead-coloring techniques in a split-bottom geometry, we reveal internal flow fields within sheared granular packings. We find robust convection rolls, strikingly governed by system geometry: at low filling heights, two counter-rotating convection rolls emerge, while at higher filling heights, a single dominant convection roll forms, featuring radially outward flow at the surface. This transition is driven by the height-dependent broadening of the shear zone, which introduces shear rate asymmetry across its flanks. Notably, the transition occurs entirely within the open shear band regime. These findings underscore the pivotal role of system geometry in shaping secondary flow formation in dense packings of frictional particles, suggesting possible broader relevance to geophysical flow dynamics and industrial applications.
title Convective Flows in Sheared Packings of Spherical Particles
topic Soft Condensed Matter
url https://arxiv.org/abs/2510.23836