Silo discharge of mixtures of soft and rigid grains

Jing Wang, Bo Fan, Tivadar Pongó, Kirsten Harth, Torsten Trittel, Ralf Stannarius*, Maja Illig, Tamás Börzsönyi, Raúl Cruz Hidalgo

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


We study the outflow dynamics and clogging phenomena of mixtures of soft, elastic low-friction spherical grains and hard frictional spheres of similar size in a quasi-two-dimensional (2D) silo with narrow orifice at the bottom. Previous work has demonstrated the crucial influence of elasticity and friction on silo discharge. We show that the addition of small amounts, even as low as 5%, of hard grains to an ensemble of soft, low-friction grains already has significant consequences. The mixtures allow a direct comparison of the probabilities of the different types of particles to clog the orifice. We analyze these probabilities for the hard, frictional and the soft, slippery grains on the basis of their participation in the blocking arches, and compare outflow velocities and durations of non-permanent clogs for different compositions of the mixtures. Experimental results are compared with numerical simulations. The latter strongly suggest a significant influence of the inter-species particle friction.

Original languageEnglish
Pages (from-to)4282-4295
Number of pages14
JournalSoft Matter
Issue number16
Early online date3 Mar 2021
Publication statusPublished - 2021


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