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Poster De Conférence Année : 2023

Systematic description of the effect of grain elongation in silo discharge

Résumé

By means of 2D Contact Dynamics simulations, we investigate the flow properties of granular materials composed of elongated grains within a silo of varying orifice size. The grains have a rounded-cap rectangular shape described by their aspect ratio parameter varying from 1 for a disk to 7 for a thin or long grain. In order to isolate the effects of grain shape, both the mass and surface of the grains are kept constant as well as the total mass of the system and the condition of the discharge. By simulating a large number of avalanches, the flow rates “Q”, the velocity profiles and the packing fraction profiles close to the orifice are studied for increasing grain aspect ratio and for various characteristic dimensionless numbers such the orifice size normalized by the grain size, or the system size normalized either by the orifice size or by the grain size. A counterintuitive finding of this work is that the effect of grain elongation depends on the size of the orifice. Indeed, we find that Q is independent of grain elongation for small (normalized) orifice size. In contrast, Q increases with grain elongation for intermediate (normalized) orifice size, and it may saturate or continue to increase at larger grain aspect ratio. Based on the methodology proposed by Janda et al. (2012) to deduce the flow rate from the packing fraction and velocity profiles close to the orifice, we show that the nonlinear variation of Q with grain elongation results from compensation mechanisms between the velocity and the packing fraction measured at the center of the orifice.
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Dates et versions

hal-04209698 , version 1 (08-11-2023)

Identifiants

  • HAL Id : hal-04209698 , version 1

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Agathe Bignon, Mathieu Renouf, Emilien Azéma. Systematic description of the effect of grain elongation in silo discharge. 9th International Conference on Discrete Element Methods (DEM9), Sep 2023, Erlangen, Germany. DEM9 Book of Abstracts. ⟨hal-04209698⟩
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