title: Heaping, secondary flows and broken symmetry in flows of elongated granular particles.
abstract: In this paper we report experiments where we shear granular rods in split-bottom geometries, and find that a significant heap of height of least 40% of the filling height can form at the particle surface. We show that heaping is caused by a significant secondary flow, absent for spherical particles. Flow reversal transiently reverses the secondary flow, leading to a quick collapse and slower regeneration of the heap. We present a symmetry argument and experimental data that show that the generation of the secondary flow is driven by a misalignment of the mean particle orientation with the streamlines of the flow. This general mechanism is expected to be important in all flows of sufficiently anisometric grains.
authors: Huygens-Kamerlingh Onnes Lab, Postbus 9504, 2300 RA Leiden, The Netherlands. wortel@physics.leidenuniv.nl.
authors: Geert
authors: G
authors: Wortel
authors: Tamás
authors: T
authors: Börzsönyi
authors: Ellák
authors: E
authors: Somfai
authors: Sandra
authors: S
authors: Wegner
authors: Balázs
authors: B
authors: Szabó
authors: Ralf
authors: R
authors: Stannarius
authors: Martin
authors: M
authors: van Hecke