Onset of Mechanical Stability in Random Packings of Frictional Spheres

Jerkins, M.; Schröter, Matthias; Swinney, Harry L.; Senden, Tim J.; Saadatfar, Mohammad; Aste, Tomaso

doi:10.1103/physrevlett.101.018301

Cited by 170 publications

(168 citation statements)

References 31 publications

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“…The length scale is L * = 2.55 m. which the definition of critical concentrations (such as the maximum random packing concentration) was more difficult. [29][30][31] When the solids fraction was in the 0.575-0.605 range, we observed three distinct regimes:…”

Section: A Regime Partitioningmentioning

confidence: 91%

Granular suspension avalanches. I. Macro-viscous behavior

2013

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We experimentally studied the flow behavior of a fixed volume of granular suspension, initially contained in a reservoir and released down an inclined flume. Here "granular suspension" refers to a suspension of non-Brownian particles in a viscous fluid. Depending on the solids fraction, density mismatch, and particle size distribution, a wealth of behaviors can be observed. Here we report and interpret results obtained with granular suspensions, which consisted of neutrally buoyant particles with a solids fraction (φ = 0.575-0.595) close to the maximum random packing fraction (estimated at φ m = 0.625). The particles had the same refractive index as the fluid, which made it possible to measure the velocity profiles inside the moving bulk and far from the sidewalls. Additional information such as the front position and the flow depth was also recorded. Three regimes were observed. At early times, the flow features were reminiscent of homogeneous Newtonian fluids (e.g., the same dependence of the front position on time). At later times, the free surface became more and more bumpy as fractures developed within the bulk. This fracture process ultimately gave rise to a stick-slip regime, in which the suspension moved intermittently. In this paper, we focus on the first regime referred to as the macroviscous regime. Although the bulk flow properties looked like those of Newtonian fluids, the internal dynamics were much richer. C 2013 American Institute of Physics.

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Section: A Regime Partitioningmentioning

confidence: 91%

Granular suspension avalanches. I. Macro-viscous behavior

2013

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“…It was demonstrated that the random loose packing volume fraction decreases with increasing inter-particle friction coefficient 1,2 . The role of friction on force chains was investigated in reference 3 .…”

Section: Introductionmentioning

confidence: 99%

Tailoring the frictional properties of granular media

et al. 2011

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A method of modifying the roughness of soda-lime glass spheres is presented, with the purpose of tuning inter-particle friction. The effect of chemical etching on the surface topography and the bulk frictional properties of grains is systematically investigated. The surface roughness of the grains is measured using white light interferometry and characterised by the lateral and vertical roughness length scales. The underwater angle of repose is measured to characterise the bulk frictional behaviour. We observe that the coefficient of friction depends on the vertical roughness length scale.

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“…In this vein, in [12] an average packing fraction of 0.55 is found for monodisperse spheres of diameter of the order of 100 μm and a packing fraction in the interval 0.50−0.55 for tetrahedrons and octahedrons [13].…”

Section: Validation Experimental Modelmentioning

confidence: 99%

DEM simulation of dendritic grain random packing: application to metal alloy solidification

2017

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Abstract. The random packing of equiaxed dendritic grains in metal-alloy solidification is numerically simulated and validated via an experimental model. This phenomenon is characterized by a driving force which is induced by the solid-liquid density difference. Thereby, the solid dendritic grains, nucleated in the melt, sediment and pack with a relatively low inertia-to-dissipation ratio, which is the so-called Stokes number. The characteristics of the particle packed porous structure such as solid packing fraction affect the final solidified product. A multi-sphere clumping Discrete Element Method (DEM) approach is employed to predict the solid packing fraction as function of the grain geometry under the solidification conditions. Five different monodisperse noncohesive frictionless particle collections are numerically packed by means of a vertical acceleration: a) three dendritic morphologies; b) spheres and c) one ellipsoidal geometry. In order to validate our numerical results with solidification conditions, the sedimentation and packing of two monodisperse collections (spherical and dendritic) is experimentally carried out in a viscous quiescent medium. The hydrodynamic similarity is respected between the actual phenomenon and the experimental model, that is a low Stokes number, o(10 −3 ). In this way, the experimental average solid packing fraction is employed to validate the numerical model. Eventually, the average packing fraction is found to highly depend on the equiaxed dendritic grain sphericity, with looser packings for lower sphericity.

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Onset of Mechanical Stability in Random Packings of Frictional Spheres

Cited by 170 publications

References 31 publications

Granular suspension avalanches. I. Macro-viscous behavior

Granular suspension avalanches. I. Macro-viscous behavior

Tailoring the frictional properties of granular media

DEM simulation of dendritic grain random packing: application to metal alloy solidification

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