Coupled continuum modeling of size-segregation driven by shear-strain-rate gradients and flow in dense, bidisperse granular media

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Hauptverfasser: Liu, Daren, Singh, Harkirat, Henann, David L.
Format: Preprint
Veröffentlicht: 2023
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author Liu, Daren
Singh, Harkirat
Henann, David L.
author_facet Liu, Daren
Singh, Harkirat
Henann, David L.
contents Dense granular systems that consist of particles of disparate sizes segregate based on size during flow, resulting in complex, coupled segregation and flow patterns. The ability to predict how granular mixtures segregate is important in the design of industrial processes and the understanding of geophysical phenomena. The two primary drivers of size-segregation are pressure gradients and shear-strain-rate gradients. In this work, we isolate size-segregation driven by shear-strain-rate gradients by studying two dense granular flow geometries with constant pressure fields: gravity-driven flow down a long vertical chute with rough parallel walls and annular shear flow with rough inner and outer walls. We perform discrete element method (DEM) simulations of dense flow of bidisperse granular systems in both flow geometries, while varying system parameters, such as the flow rate, flow configuration size, fraction of large/small grains, and grain-size ratio, and use DEM data to inform continuum constitutive equations for the relative flux of large and small particles. When the resulting continuum model for the dynamics of size-segregation is coupled with the nonlocal granular fluidity model (a nonlocal continuum model for dense granular flow rheology), we show that both flow fields and segregation dynamics may be simultaneously captured using this coupled, continuum system of equations.
format Preprint
id arxiv_https___arxiv_org_abs_2301_11453
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Coupled continuum modeling of size-segregation driven by shear-strain-rate gradients and flow in dense, bidisperse granular media
Liu, Daren
Singh, Harkirat
Henann, David L.
Soft Condensed Matter
Dense granular systems that consist of particles of disparate sizes segregate based on size during flow, resulting in complex, coupled segregation and flow patterns. The ability to predict how granular mixtures segregate is important in the design of industrial processes and the understanding of geophysical phenomena. The two primary drivers of size-segregation are pressure gradients and shear-strain-rate gradients. In this work, we isolate size-segregation driven by shear-strain-rate gradients by studying two dense granular flow geometries with constant pressure fields: gravity-driven flow down a long vertical chute with rough parallel walls and annular shear flow with rough inner and outer walls. We perform discrete element method (DEM) simulations of dense flow of bidisperse granular systems in both flow geometries, while varying system parameters, such as the flow rate, flow configuration size, fraction of large/small grains, and grain-size ratio, and use DEM data to inform continuum constitutive equations for the relative flux of large and small particles. When the resulting continuum model for the dynamics of size-segregation is coupled with the nonlocal granular fluidity model (a nonlocal continuum model for dense granular flow rheology), we show that both flow fields and segregation dynamics may be simultaneously captured using this coupled, continuum system of equations.
title Coupled continuum modeling of size-segregation driven by shear-strain-rate gradients and flow in dense, bidisperse granular media
topic Soft Condensed Matter
url https://arxiv.org/abs/2301.11453