Flow and clogging in a silo with an obstacle above the orifice

Lozano, Celia; Janda, Álvaro; Garcimartín, Ángel; Maza, Diego; Zuriguel, Iker

doi:10.1103/physreve.86.031306

Cited by 60 publications

(45 citation statements)

References 37 publications

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“…This result contrasts with a numerical work in which the flow rate shows a peak at a certain L [13]. Although the similar flow rate peak has been reported in experiment [14], its peaks are not very clear. While the current data rather show dips at certain L, it is difficult to identify the clear peak of Q.…”

Section: Flow Ratecontrasting

confidence: 55%

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Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

Endo

Katsuragi

2017

EPJ Web Conf.

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Abstract. Two-dimensional granular discharge flow driven by gravity under the influence of an obstacle is experimentally investigated. A horizontal exit of width W is opened at the bottom of vertical Hele-Shaw cell filled with stainless-steel particles to start the discharge flow. In this experiment, a circular obstacle is placed in front of the exit. Thus, the distance between the exit and obstacle L is also an important parameter. During the discharge, granular-flow state is acquired by a high-speed camera. The bulk discharge-flow rate is also measured by load cell sensors. The obtained high-speed-image data are analyzed to clarify the particle-level granular-flow dynamics. Using the measured data, we find that the obstacle above the exit affects the granularflow field. Specifically, the existence of obstacle results in large horizontal granular temperature and small packing fraction. This tendency becomes significant when L is smaller than approximately 6D g when W 4D g , where D g is diameter of particles.

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Section: Flow Ratecontrasting

confidence: 55%

“…The systematic examination with various W and obstacle size like Ref. [14] could also be an interesting future problem.…”

Section: Discussionmentioning

confidence: 99%

Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

Endo

Katsuragi

2017

EPJ Web Conf.

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“…Let us also remark that we have only performed this experiment with the obstacle at a fixed position. In order to find the optimal reduction of the clogging probability, the distance to the door is crucial [32][33][34]. This exploration is costly in terms of the time needed and we have not attempted it.…”

Section: Enhancementsmentioning

confidence: 99%

Flow and clogging of a sheep herd passing through a bottleneck

et al. 2015

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We present an experimental study of a flock passing through a narrow door. Video monitoring of daily routines in a farm has enabled us to collect a sizable amount of data. By measuring the time lapse between the passage of consecutive animals, some features of the flow regime can be assessed. A quantitative definition of clogging is demonstrated based on the passage time statistics. These display broad tails, which can be fitted by power laws with a relatively large exponent. On the other hand, the distribution of burst sizes robustly evidences exponential behavior. Finally, borrowing concepts from granular physics and statistical mechanics, we evaluate the effect of increasing the door size and the performance of an obstacle placed in front of it. The success of these techniques opens new possibilities regarding their eventual extension to the management of human crowds.

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“…The large time lapses ∆t between successive escapes, forming the tail of p (∆t), are dominated by the time that vibrations take to break these arches. Lozano and co-workers elucidated that the extent of time an arch resists vibrations on average is controlled by its weakest point, i.e., the grain which forms the largest angle with its two neighbors in the arch [28]. Geometry, and more specifically the variable weaknesses of the arches depending on their geometry, thus plays a central role.…”

Section: III Presentation Of the Contagion-free Modelmentioning

confidence: 99%

Statistical fluctuations in pedestrian evacuation times and the effect of social contagion

Nicolas¹,

Bouzat²,

Kuperman³

2016

Phys. Rev. E

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Mathematical models of pedestrian evacuation and the associated simulation software have become essential tools for the assessment of the safety of public facilities and buildings. While a variety of models are now available, their calibration and test against empirical data are generally restricted to global, averaged quantities; the statistics compiled from the time series of individual escapes ("microscopic" statistics) measured in recent experiments are thus overlooked. In the same spirit, much research has primarily focused on the average global evacuation time, whereas the whole distribution of evacuation times over some set of realizations should matter. In the present paper we propose and discuss the validity of a simple relation between this distribution and the "microscopic" statistics, which is theoretically valid in the absence of correlations. To this purpose, we develop a minimal cellular automaton, with novel features that afford a semi-quantitative reproduction of the experimental "microscopic" statistics. We then introduce a process of social contagion of impatient behavior in the model and show that the simple relation under test may dramatically fail at high contagion strengths, the latter being responsible for the emergence of strong correlations in the system. We conclude with comments on the potential practical relevance for safety science of calculations based on "microscopic" statistics.

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Flow and clogging in a silo with an obstacle above the orifice

Cited by 60 publications

References 37 publications

Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

Flow and clogging of a sheep herd passing through a bottleneck

Statistical fluctuations in pedestrian evacuation times and the effect of social contagion

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