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Flocking at a distance in active granular matter

Kumar, Nitin and Soni, Harsh and Ramaswamy, Sriram and Sood, AK (2014) Flocking at a distance in active granular matter. In: NATURE COMMUNICATIONS, 5 .

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Official URL: http://dx.doi.org/ 10.1038/ncomms5688


The self-organized motion of vast numbers of creatures in a single direction is a spectacular example of emergent order. Here, we recreate this phenomenon using actuated nonliving components. We report here that millimetre-sized tapered rods, rendered motile by contact with an underlying vibrated surface and interacting through a medium of spherical beads, undergo a phase transition to a state of spontaneous alignment of velocities and orientations above a threshold bead area fraction. Guided by a detailed simulation model, we construct an analytical theory of this flocking transition, with two ingredients: a moving rod drags beads; neighbouring rods reorient in the resulting flow like a weathercock in the wind. Theory and experiment agree on the structure of our phase diagram in the plane of rod and bead concentrations and power-law spatial correlations near the phase boundary. Our discovery suggests possible new mechanisms for the collective transport of particulate or cellular matter.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the NATURE PUBLISHING GROUP, MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 14 Nov 2014 07:28
Last Modified: 14 Nov 2014 07:28
URI: http://eprints.iisc.ac.in/id/eprint/50273

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