Segregation in a dense, inclined, granular flow with basal layering

Jenkins, James T.; Larcher, Michele

doi:10.1007/s10035-020-0996-1

Cited by 4 publications

(3 citation statements)

References 28 publications

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“…However, on an erodible bed, we predict a qualitatively different regime, with a double-segregation profile consisting of large particles localized both at the top and bottom of the flow and small particles in the middle. Similar profiles were previously predicted [26].…”

Section: Segregationsupporting

confidence: 89%

Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases

Jenkins

Larcher

2023

Water

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Kinetic theory is used to propose and solve boundary value problems for fully developed, steady, dense gravity-driven flows of mixtures composed of identical inelastic spheres and water over both inclined erodible beds and rigid, bumpy bases confined by vertical sidewalls. We solve the boundary value problems assuming values of the mass density and of the size of the spheres typical of natural materials and show the numerical solutions for the profiles of the mean velocities of the particles and fluid, the intensity of the particle velocity fluctuations, and the granular concentration. In addition, we indicate how the features of the grain velocity fluctuations profile would influence segregation in three situations when the particle phase consists of two sizes of spheres: (1) the spheres are of the same material, and only gradients of temperature influence their segregation; (2) the mass densities of the material of the spheres are such that only gravity influences segregation; and (3) the mass densities are such that the coefficients of the temperature gradients and gravity segregation mechanisms are equal. For spheres of the same material, over a rigid bumpy base, the concentration of larger spheres increases from zero at the bed to the maximum value at the top of the flow; while over an erodible bed, this concentration has its maximum value at both the bed and the top of the flow.

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Section: Segregationsupporting

confidence: 89%

Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases

Jenkins

Larcher

2023

Water

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“…This is apparently different from segregation in gravity-driven flows at moderate inclination angle, but vertical temperature gradients can also play a role in these. Segregation driven by temperature gradients may be understood in the framework of the kinetic theory for binary mixtures of dense granular gases (Arnarson & Jenkins 2004; Garzó 2008, 2009; Larcher & Jenkins 2013, 2015; Jenkins & Larcher 2020). We anticipate that this kinetic theory, based on instantaneous, pairwise collisions alone, is, for the value of the sliding friction employed in the simulations, relevant until a mixture concentration of 0.60.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Particle segregation in inclined high-speed granular flows

Neveu¹,

Larcher

Delannay³

et al. 2022

J. Fluid Mech.

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We report on the discovery, using numerical simulations, of a segregation pattern in high-speed granular flows, in which size segregation is primarily driven by two-dimensional granular temperature gradients, rather than by gravity. In contrast to slower flows on gentle slopes, in high-speed flows on steep slopes, large particles no longer accumulate in the upper layers of the flow, but are trapped in the interior. The strong temperature gradients that develop between the interior of the flow and the surrounding dilute periphery appear to govern the segregation mechanism. Interestingly, these new segregated flows run at a much faster speed than similar monodisperse flows. This opens up promising perspectives for transporting granular material with enhanced efficiency. Importantly, we show that the kinetic theory for dense, inclined flows of binary mixtures can provide a relevant theoretical framework to explain the segregation patterns observed in the numerical simulations.

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“…It also means that high temperature increase can be expected, at least locally. Theoretical models for the rheology of solid flows have been proposed and enriched with new physics, based for example on the kinetic theory or on the µ(I) rheology [49][50][51][52]. But such theories are lacking in the range of loads, of temperatures and of shear rates that exist in the systems at stake here (not even mentioning the fact that the third body is a highly transformed and heterogeneous material, and therefore very different from that composing the first bodies).…”

Section: Some Challenges I Experimental Validationmentioning

confidence: 99%

Confined sheared flows of hard and soft granular materials: Some challenges in tribology and fault mechanics

et al. 2022

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This paper belongs to a Focus Series dedicated to Challenges in Granular Matter. As such, it does not report any new finding, but rather offers an overview of the state of the art and of current and future challenges for the granular physics community. The focus is placed on the case of confined sheared flows of granular samples with particular complexities, such as soft, angular, or cemented grains, with applications in tribology and fault mechanics. We first explain why granular science may help to improve our understanding of dry friction in these two applications, and illustrate some recently unveiled aspects regarding the complexity of the problem. We then describe a few avenues for future research on the topic, focusing on the dialogue between simulations and experiments, on scale-related challenges, and on some pivotal computational aspects.

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Segregation in a dense, inclined, granular flow with basal layering

Cited by 4 publications

References 28 publications

Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases

Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases

Particle segregation in inclined high-speed granular flows

Confined sheared flows of hard and soft granular materials: Some challenges in tribology and fault mechanics

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