Jamming of Granular Flow in a Two-Dimensional Hopper

To, Kiwing; Lai, Pik Yin; Pak, Hyuk Kyu

doi:10.1103/physrevlett.86.71

Cited by 399 publications

(381 citation statements)

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“…To et al [13], To and Lai [14] reported that clogging arches have a semi-circular convex shape, which can be reproduced by a restricted random walk model. Note that a convex shape is, indeed, a necessary condition for the static equilibrium of The big white square marks the zone that has been considered as the bulk region, as justified in the text.…”

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confidence: 99%

“…In all these systems clogging arches withstand the weight of the particles above them just as architectural arches do. For the case of silos, a link has been sought between the properties of the arches and the clogging probability [13,14,22,23]. Although the relationship is not fully understood, the knowledge about the properties of these assemblies has been notably improved.…”

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confidence: 99%

“…Familiar examples of clogging appear in crowd stampedes [9,10], fluid-driven particle flows [11,12], and granular materials. In this later case, abundant research has been carried out covering 2D [13,14] and 3D [15,16] silos, inclined outpouring [17,18], silos with an obstacle above the outlet [19], anisometric (wedge) hoppers [20], and piles discharged through an orifice at their bottom [21]. In all these systems clogging arches withstand the weight of the particles above them just as architectural arches do.…”

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Force analysis of clogging arches in a silo

et al. 2013

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In this work, we examine a quasi-2D silo that clogs due to the spontaneous formation of stable arches. We validate a numerical scheme comparing the morphology of clogging arches with previous experimental findings. Additionally, we inspect the forces that act on particles, both on those in the bulk of the silo as well as those belonging to the arches formed above the outlet. In the silo, we have found that normal forces are higher close to the wall, in contrast to the central part of the silo, where normal forces are notably lower. Besides, it is revealed that normal forces on particles belonging to the clogging arches are significantly larger than in their surroundings. In a particle of the arch, the magnitude of the force strongly depends on the angle subtended from its center to the contact points with its two neighbors in the arch. Indeed, for angles exceeding 180 • , the larger the angle, the lower the normal force and the higher the tangential one. On the contrary, for smaller angles the behavior is reversed, so the normal forces increase with the angle. Finally, we present a comparison of the normal and tangential force distributions for the particles within the arch and in the bulk. All this shows the special nature of the forces developed in clogging arches, which suggests that direct extrapolations of bulk properties should not be taken for granted.

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Force analysis of clogging arches in a silo

et al. 2013

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“…The surface of grains is usually rough, thus leading to speciÿc angles of repose [11]. Also, the grain anisotropy leads to phenomena like jams [12], in ow, and arches [13], in static structures. It seems therefore necessary to have at least one degree of freedom in order to describe grains; we are even aware that only one degree is a very strong approximation.…”

Section: Introductionmentioning

confidence: 99%

Magnetically controlled ballistic deposition. A model of polydisperse granular packing

Trojan

Ausloos²

2003

Physica A: Statistical Mechanics and its Applications

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The ow and deposition of polydisperse granular materials is simulated through the magnetic di usion limited aggregation (MDLA) model. The random walk undergone by an entity in the MDLA model is modiÿed such that the trajectories are ballistic in nature, leading to a magnetically controlled ballistic deposition (MBD) model. This allows to obtain important ingredients about a di cult problem that of the nonequilibrium segregation of polydisperse sandpiles and heterogeneous adsorption of a binary distribution of particles which can interact with each other and with an external ÿeld. Our detailed results from many simulations of MBD clusters on a two-dimensional triangular lattice above a at surface in a vertical ÿnite size box for binary systems indicates intriguing variations of the density, "magnetization", types of clusters and fractal dimensions. We derive the ÿeld and grain interaction-dependent susceptibility and compressibility. We deduce a completely new phase diagram for binary granular piles and discuss its complexity inherent to di erent grain competition and cluster growth probabilities.

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“…Quantitative predictions for flow rates were proposed (e. g. [5][6][7][8] and references therein). When the outlet diameter is smaller than about 5 particle diameters [9][10][11][12][13], clogs form after some time at the orifice and block further outflow, mostly unwanted. Spontaneous arch formation [14,15], the preceding kinetics [16], as well as the inherent force distributions [17,18] have been analyzed in the literature.…”

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Silo outflow of soft frictionless spheres

et al. 2017

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Outflow of granular materials from silos is a remarkably complex physical phenomenon that has been extensively studied with simple objects like monodisperse hard disks in two dimensions (2D) and hard spheres in 2D and 3D. For those materials, empirical equations were found that describe the discharge characteristics. Softness adds qualitatively new features to the dynamics and to the character of the flow. We report a study of the outflow of soft, practically frictionless hydrogel spheres from a quasi-2D bin. Prominent features are intermittent clogs, peculiar flow fields in the container and a pronounced dependence of the flow rate and clogging statistics on the container fill height. The latter is a consequence of the ineffectiveness of Janssen's law: the pressure at the bottom of a bin containing hydrogel spheres grows linearly with the fill height.

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Jamming of Granular Flow in a Two-Dimensional Hopper

Cited by 399 publications

References 4 publications

Force analysis of clogging arches in a silo

Force analysis of clogging arches in a silo

Magnetically controlled ballistic deposition. A model of polydisperse granular packing

Silo outflow of soft frictionless spheres

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