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Issue 20, 2013
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Signatures of incipient jamming in collisional hopper flows

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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

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Publication details

The article was received on 30 Nov 2012, accepted on 26 Mar 2013 and first published on 10 Apr 2013

Article type: Paper
DOI: 10.1039/C3SM27760G
Soft Matter, 2013,9, 5016-5024

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    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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