Universität zu Köln

Elekes, Filip ORCID: 0000-0002-7258-3386 and Parteli, Eric J. R. (2021). An expression for the angle of repose of dry cohesive granular materials on Earth and in planetary environments. Proc. Natl. Acad. Sci. U. S. A., 118 (38). WASHINGTON: NATL ACAD SCIENCES. ISSN 1091-6490

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Abstract

The angle of repose-i.e., the angle theta r between the sloping side of a heap of particles and the horizontal-provides one of the most important observables characterizing the packing and flowability of a granular material. However, this angle is determined by still poorly understood particle-scale processes, as the interactions between particles in the heap cause resistance to roll and slide under the action of gravity. A theoretical expression that predicts theta(r) as a function of particle size and gravity would have impact in the engineering, environmental, and planetary sciences. Here we present such an expression, which we have derived from particle-based numerical simulations that account for both sliding and rolling resistance, as well as for nonbonded attractive particle-particle interactions (van der Waals). Our expression is simple and reproduces the angle of repose of experimental conical heaps as a function of particle size, as well as theta(r) obtained from our simulations with gravity from 0.06 to 100 times that of Earth. Furthermore, we find that heaps undergo a transition from conical to irregular shape when the cohesive to gravitational force ratio exceeds a critical value, thus providing a proxy for particle-scale interactions from heap morphology.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Elekes, Filip UNSPECIFIED orcid.org/0000-0002-7258-3386 UNSPECIFIED Parteli, Eric J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-571232
DOI:	10.1073/pnas.2107965118
Journal or Publication Title:	Proc. Natl. Acad. Sci. U. S. A.
Volume:	118
Number:	38
Date:	2021
Publisher:	NATL ACAD SCIENCES
Place of Publication:	WASHINGTON
ISSN:	1091-6490
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ROLLING RESISTANCE; GRAVITY; POWDERS; MODELS; SHEAR; SIMULATIONS; COEFFICIENT; RESTITUTION; VALIDATION; FRICTION Multiple languages Multidisciplinary Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/57123