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DY: Fachverband Dynamik und Statistische Physik
DY 13: Granular Physics 3 - organized by Matthias Sperl (Köln)
DY 13.7: Talk
Monday, March 22, 2021, 17:00–17:20, DYc
Intermittent flow and transient congestions of soft low-friction spheres in silo discharge — •Jing Wang1, Kirsten Harth1, Ralf Stannarius1, and Tamas Börzsönyi2 — 1Institute of Physics, Otto von Guericke University, Magdeburg, Germany — 2Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Budapest, Hungary
During discharge of hard particles from a silo with a small orifice at the bottom, grains flow freely only when the orifice size at least 5 times the particle diameter. The outflow rate is practically independent of the fill level. Below a certain outlet diameter, hard particles reach stable clogs, which can only be destroyed by external forcing. We study soft, low-friction particles (hydrogel beads) that show very different, peculiar features during discharge: They flow freely even when the orifice is only slightly larger than two particle diameters. At small orifice sizes, strong fluctuations of the flow velocity set in. Non-permanent congestions are characteristic that have previously been described only for lifestock or pedestrians passing narrow gates or exits, but never for inanimate hard granular material. We present experimental data recorded in a 2D silo.
This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812638 and DFG Grant HA8467/2-1. [1] K. Harth et al., Soft Matter 16 8013 (2020).