Decoupling Geometrical and Kinematic Contributions to the Silo Clogging Process

Gella, Diego; Zuriguel, Iker; Maza, Diego

doi:10.1103/physrevlett.121.138001

“…Nevertheless, we still expect that hopper geometries lead to clogging reduction for a polydisperse sample as the restriction imposed by the hopper in the angles between particles holds in this case. Also, other features such as the extrapolation to a three-dimensional case, or the effect of the particles' dynamics [33] (which could slightly vary in the range of 3 < D/d 4 leading to changes in the mean avalanche size) should be studied in the future.…”

Section: Discussionmentioning

confidence: 99%

Effect of hopper angle on granular clogging

López-Rodríguez

¹

,

Gella

²

,

To

³

et al. 2019

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We present experimental results of the effect of the hopper angle on the clogging of grains discharged from a two-dimensional silo under gravity action. We observe that the probability of clogging can be reduced by three orders of magnitude by increasing the hopper angle. In addition, we find that for very large hopper angles, the avalanche size (s) grows with the outlet size (D) stepwise, in contrast to the case of a flat-bottom silo for which s grows smoothly with D. This surprising effect is originated from the static equilibrium requirement imposed by the hopper geometry to the arch that arrests the flow. The hopper angle sets the bounds of the possible angles of the vectors connecting consecutive beads in the arch. As a consequence, only a small and specific portion of the arches that jam a flat-bottom silo can survive in hoppers.

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“…The fitting results ( H / d p , α ( H / d p )) are plotted in Figure 7(d) as red scatters. Since exponential relationships are broadly used to analyze clogging or jamming problems, 63,64,65 we adopt the exponential function to quantify the dependence of α on H / d p ,

α = e^{a + b ((), normalH / d_{p})},

where a = − 4.19 ± 0.22, b = 0.41 ± 0.042 are fitting parameters. Equation () is displayed as the black line in Figure 7(d) and shows high fitting accuracy.…”

Section: Resultsmentioning

confidence: 99%

Mechanism for clogging of microchannels by small particles with liquid cohesion

Shao

¹

,

Ruan

²

,

Li

³

2021

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We numerically investigate the effect of liquid cohesion on the clogging of microchannels induced by small wet particles. The computer simulation is performed by the discrete element method (DEM) with cohesive contact models in presence of pendular liquid bridges, which is embedded into the computational fluid dynamics (CFD). We find that liquid cohesion significantly promotes particle deposition and agglomerate growth. A clogging phase diagram, in the form of Weber number and Stokes number, is constructed to quantify the clogging‐nonclogging transition. The competition between particle–particle and particle–fluid interactions is quantitatively discussed in terms of particle velocity and slip velocity. Strong cohesion can address a greater slip velocity or drag between particles and fluid, which depresses the resuspension of deposited particles and results in clogging. Finally, we compare our results with clogging induced by van der Waals adhesion of small dry particles and find that the competence of liquid cohesion is more prominent.

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“…J inf represents the clogging probability when h tends towards infinity. is value depends on other parameters (like orifice size) of the system, and there exist some empirical models of this value [11]. C 1 and C 2 are the fitting parameters.…”

Section: Resultsmentioning

confidence: 99%

“…From the pioneering work of To et al in 2001 [6], we know that magnitude of clogging probability J changes greatly with the outlet size. Furthermore, the existence of a critical outlet size above which the flow may never get jammed remains debatable [11]. Subsequently, it has been experimentally and numerically shown that some methods can reduce the probability of clogging by, for example, putting an obstacle above the exit [12,13] and applying a helical texture to the pipes' inner wall [14].…”

Section: Introductionmentioning

confidence: 99%

Study of Clogging Phenomenon for a Conical Hopper: The Influence of Particle Bed Height and Hopper Angle

Khalid

¹

,

Zhou

²

2021

Science and Technology of Nuclear Installations

0

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The granular flow is one of the principal issues for the design of pebble bed reactors. Particularly, the clogging phenomenon raises an important issue for pebble bed reactors. In this paper, we conduct experiments and discrete particle simulation of two-dimensional discharge granular flow from a conical hopper, to study the effect of the particle bed height h and hopper angle α on the clogging phenomenon. In general, the clogging probability J increases with height h and starts to saturate when h is larger than a critical value. The experimental result trends are supported by discrete simulations. To understand the underlying physical mechanism, we conduct discrete particle simulations for various h values, focusing on the following parameters: the statistical averaging of the volume fraction, velocity, and contact pressure of particles near the aperture during the discharge. We found that, among all relevant variables, the contact pressure of particles is the main cause of the increasement of J when h increases. An exponential law between the pebble bed h and clogging probability J has been established based on these observations and Janssen model. As for hopper angle α , J shows an almost constant behavior for any rise in α followed by a sudden regression at α = 75 ° . Surprisingly, the effect of α is most obvious for intermediate values of h , where we observe a sharp increasement of clogging probability. The same trend is observed in the two-dimensional discrete simulation results.

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Decoupling Geometrical and Kinematic Contributions to the Silo Clogging Process

Cited by 27 publications

References 35 publications

Effect of hopper angle on granular clogging

Effect of hopper angle on granular clogging

Mechanism for clogging of microchannels by small particles with liquid cohesion

Study of Clogging Phenomenon for a Conical Hopper: The Influence of Particle Bed Height and Hopper Angle

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