Orientation, flow, and clogging in a two-dimensional hopper: Ellipses vs. disks

¹ Department of Physics & Center for Nonlinear and Complex Systems, Duke University - Durham, NC, 27708, USA
² 10451 Clay Road, TGS-Nopec Geophysical Co. - Houston, TX, 77043, USA

Received: 21 October 2015
Accepted: 11 May 2016

Abstract

Two-dimensional (2D) hopper flow of disks has been extensively studied. Here, we investigate hopper flow of ellipses with aspect ratio , and we contrast that behavior to the flow of disks. We use a quasi-2D hopper containing photoelastic particles to obtain stress/force information. We simultaneously measure the particle motion and stress. We determine several properties, including discharge rates, clogging probabilities, and the number of particles in clogging arches. For both particle types, the size of the opening, D, relative to the size of particles, ℓ, is an important dimensionless measure. The orientation of the ellipses plays an important role in flow rheology and clogging. The alignment of contacting ellipses enhances the probability of forming stable arches. This study offers insights into applications involving the flow of granular materials consisting of ellipsoidal shapes, and possibly other non-spherical shapes.