Simulations and physical measurements of glass spheres flowing down a bumpy incline

Hanes, Daniel M.; Walton, Otis R.

doi:10.1016/s0032-5910(99)00232-6

Cited by 85 publications

(65 citation statements)

References 18 publications

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“…The upper bound for SFD flows is also provided, but as correctly pointed out by Ref. [33] the attainment of SFD flows is restricted by the physical length of the chute, and hence so is the maximal angle above which an "accelerated regime" is observed. Numerical simulations can be used in order to complement these experimental results, but literature on numerical studies over flat frictional surfaces is sparse.…”

Section: The State Of the Art On Granular Flows Down Inclined Chamentioning

confidence: 83%

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Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

2013

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Granular flows down inclined channels with smooth boundaries are common in nature and industry. Nevertheless, flat boundaries have been much less investigated than bumpy ones, which are used by most experimental and numerical studies to avoid sliding effects. Using numerical simulations of each grain and of the side walls we recover quantitatively experimental results. At larger angles we predict a rich behavior, including granular convection and inverted density profiles suggesting a Rayleigh-Bénard type of instability. In many aspects flows on a flat base can be seen as flows over an effective bumpy base made of the basal rolling layer, giving Bagnold-type profiles in the overburden. We have tested a simple viscoplastic rheological model [Nature (London) 441, 727 (2006)] in average form. The transition between the unidirectional and the convective flows is then clearly apparent as a discontinuity in the constitutive relation.

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Section: The State Of the Art On Granular Flows Down Inclined Chamentioning

confidence: 83%

“…15(a) and 15(b) of Ref. [33], where similar profiles were computed on a bumpy base with flat frictional walls. The highest temperatures occur near the center of the base (Fig.…”

Section: Mean Velocity and Fluctuationsmentioning

confidence: 93%

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

2013

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“…Such flows have been previously characterized both experimentally [2,3,4,5,6,7,8,9] and via simulation [10,11,12,13,14,15,16]. In this work we address, through large-scale discrete element simulations, the change in the flow field in the material as a function of interparticle adhesion.…”

Section: Introductionmentioning

confidence: 99%

Plug flow and the breakdown of Bagnold scaling in cohesive granular flows

et al. 2005

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Cohesive granular media flowing down an inclined plane are studied by discrete element simulations. Previous work on cohesionless granular media demonstrated that within the steady flow regime where gravitational energy is balanced by dissipation arising from intergrain forces, the velocity profile in the flow direction scales with depth in a manner consistent with the predictions of Bagnold. Here we demonstrate that this Bagnold scaling does not hold for the analogous steadyflows in cohesive granular media. We develop a generalization of the Bagnold constitutive relation to account for our observation and speculate as to the underlying physical mechanisms responsible for the different constitutive laws for cohesive and noncohesive granular media.

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“…This influence has been reported in nature [e.g., Berti et al, 2000;Swartz and McArdell, 2005] and laboratory experiments [e.g., Hanes and Walton, 2000;Parsons et al, 2001;du Pont et al, 2003;Bi et al, 2005]. Conversely, several studies propose that wall effects are negligible in their experiments [e.g., Forterre and Pouliquen, 2001;Jain et al, 2002;Tegzes et al, 2002].…”

Section: Flow Dynamicsmentioning

confidence: 81%

Correction to “Experimental study of bedrock erosion by granular flows”

Hsu¹,

Dietrich²,

Sklar³

2008

J. Geophys. Res.

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[1] Field studies suggest that bedrock incision by granular flows may be the primary process cutting valleys in steep, unglaciated landscapes. An expression has been proposed for debris flow incision into bedrock which posits that erosion rate depends on stresses due to granular interactions at the snout of debris flows. Here, we explore this idea by conducting laboratory experiments to test the hypothesis that bedrock erosion is related to grain collisional stresses which scale with shear rate and particle size. We placed granular material in a 56-cm-diameter rotating drum to explore the relationship between erosion of a synthetic bedrock sample and variables such as grain size, shear rate, water content, and bed strength. Grain collisional stresses are estimated as the inertial stress using the product of the squares of particle size and vertical shear rate. Our uniform granular material consisted of 1-mm sand and quartzite river gravel with means of 4, 6, or 10 mm. In 67 experimental runs, the eroded depth of the bed sample varied with inertial stresses in the granular flow to a power less than 1.0 and inversely with the bed strength. The flows tended to slip on smooth boundaries, resulting in higher erosion rates than no-slip cases. We found that lateral wall resistance generated shear across the channel, producing two cells whose widths depended on wall roughness. While the hypothesized inertial stress dependency is supported with these data, wear mechanics needs to account for grain dynamics specifically at the snout and possibly to include lateral shear effects.

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Simulations and physical measurements of glass spheres flowing down a bumpy incline

Cited by 85 publications

References 18 publications

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

Plug flow and the breakdown of Bagnold scaling in cohesive granular flows

Correction to “Experimental study of bedrock erosion by granular flows”

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