Discharge of vibrated granular silo: A grain scale approach

[Display omitted] •Silo discharge of granular matter can be tuned with vibrations.•Two regimes for the flow governed by the Froude number and relative frequency.•Vibrations induce periodic velocity fluctuations around the gravity-driven flow.•First regime: small fluctuations induce more contacts and...

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Published in:Powder technology 2022-01, Vol.397, p.116998, Article 116998
Main Authors: Pascot, Arthur, Morel, Jean-Yves, Antonyuk, Sergiy, Jenny, Mathieu, Cheny, Yoann, Kiesgen De Richter, Sébastien
Format: Article
Language:English
Subjects:
Atmospheric and Oceanic Physics
Fluid Dynamics
Fluid mechanics
General Physics
Geophysics
Granular material
Hopper flow
Mechanics
Ocean, Atmosphere
Physics
Rheology
Sciences of the Universe
Vibrations
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Summary:[Display omitted] •Silo discharge of granular matter can be tuned with vibrations.•Two regimes for the flow governed by the Froude number and relative frequency.•Vibrations induce periodic velocity fluctuations around the gravity-driven flow.•First regime: small fluctuations induce more contacts and a lower mean flow rate.•Second regime: fluctuations surpass gravity creating an intermittent shock dynamic. The present work focuses on granular flows in a nearly-2D silo when external vibrations are applied. Experimental measurements and numerical simulations based on discrete element method (DEM) were performed in order to study the impact of both vibrations and opening size on the flow. Although vibrations make the flow possible for small opening sizes, we show that they can either increase or decrease the flow rate depending on the range of experimental parameters (amplitude, frequency, opening size...). The effect of vibrations amplitude (10–16000 μm) and frequency (15–75 Hz) on the flow was investigated. Two regimes are evidenced for the flow, governed by the Froude number Fr and the relative frequency Ω. In the first regime, vibration causes dead zones to flow and increases collision dissipation at the aperture while keeping the particle volume fraction constant. The flow rate decreases and can be described by Benyamine's law by introducing an effective velocity that accounts for the effect of vibrations on the fall of particles at the outlet. In the second regime, the perturbations due to vibrations then surpass the gravity driven flow, leading to periodic shocks in the silo and increasing the apparent flow rate.
ISSN:0032-5910
1873-328X
DOI:10.1016/j.powtec.2021.11.042