Bulletin of the American Physical Society
APS March Meeting 2012
Volume 57, Number 1
Monday–Friday, February 27–March 2 2012; Boston, Massachusetts
Session Z43: Invited Session: Applications of Jamming
11:15 AM–2:15 PM,
Friday, March 2, 2012
Sponsoring Units: GSNP DFD
Chair: Lisa Manning, Syracuse University
Abstract ID: BAPS.2012.MAR.Z43.5
Abstract: Z43.00005 : Active Jamming: Self-propelled particles at high density*
1:39 PM–2:15 PM
Preview Abstract Abstract
What determines the mechanical properties of dense collections of active particles? The answer to this question is highly relevant to a wide range of physical and biological phenomena from tissue formation to the dynamics of vibrated granular layers. We present a numerical study of the phases and dynamics of a dense collection of self-propelled particles with soft repulsive interactions and polar alignment in a two-dimensional confined geometry. The phase diagram consists of a polar liquid phase at low packing fraction and high self-propulsion speed, and an active jammed phase at high density and low self-propulsion speed. The liquid phase exhibits local alignment and giant number fluctuations typical of the Vicsek class of models. The dynamics of the jammed phase is dominated by oscillations along the low frequency modes of the underlying packing. We show analytically that at long times the energy is carried entirely by the lowest available excitations of the system. Recent experiments on epithelial cell monolayers using force traction microscopy have revealed stress distributions that resemble those observed in granular materials. We measure and compare the local stresses in our active system, with added attraction, to both granular materials and the tissue experiments.
*This work was done in collaboration with Yaouen Fily and M. Cristina Marchetti and supported by the NSF through grants DMR-0806511 and DMR-1004789. The computations were carried out on SUGAR, a cluster supported by NSF-PHY-1040231.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.MAR.Z43.5
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