Issue 20, 2013

Signatures of incipient jamming in collisional hopper flows

Abstract

Many disordered systems experience a transition from a fluid-like state to a solid-like state following a sudden arrest in dynamics called jamming. In contrast to jamming in spatially homogeneous systems, jamming in hoppers occurs under extremely inhomogeneous conditions as the gravity-driven flow of grains enclosed by rigid walls converges towards a small opening. In this work, we study velocity fluctuations in a collisional flow near jamming using event-driven simulations. The average flow in a hopper geometry is known to have strong gradients, especially near the walls and the orifice. We find, in addition, a spatially heterogeneous distribution of fluctuations, most striking in the velocity autocorrelation relaxation times. At high flow rates, the flow at the center has lower kinetic temperatures and longer autocorrelation times than at the boundary. Remarkably, however, this trend reverses itself as the flow rate slows, with fluctuations relaxing more slowly at the boundaries though the kinetic temperatures remain high in that region. The slowing down of the dynamics is accompanied by increasing non-Gaussianity in the velocity distributions, which also have large spatial variations.

Graphical abstract: Signatures of incipient jamming in collisional hopper flows

Article information

Article type
Paper
Submitted
30 Nov 2012
Accepted
26 Mar 2013
First published
10 Apr 2013

Soft Matter, 2013,9, 5016-5024

Signatures of incipient jamming in collisional hopper flows

S. Tewari, M. Dichter and B. Chakraborty, Soft Matter, 2013, 9, 5016 DOI: 10.1039/C3SM27760G

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