2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session L8: Jamming at Nonzero Temperature and Stress
2:30 PM–5:30 PM,
Tuesday, March 17, 2009
Room: 414/415
Sponsoring
Units:
DCMP GSNP
Chair: Vincenzo Vitelli, University of Pennsylvania
Abstract ID: BAPS.2009.MAR.L8.3
Abstract: L8.00003 : Rigidity vs. Glass transition of a granular system close to Jamming
3:42 PM–4:18 PM
Preview Abstract
Abstract
Author:
Olivier Dauchot
(CEA-Saclay SPEC/GIT)
``Jamming'' is associated with two rather different notions, not
always well
distinguished in the literature. One, the glass transition, is
that of
dynamical arrest and the divergence of the structural relaxation
time, the
second, the proper jamming transition, is the appearance of
mechanical
rigidity. Both may in principle be different.
In the past few years we have investigated the dynamics of a
bi-disperse
monolayer of disks under two different mechanical forcing i.e.
cyclic shear
and horizontal vibrations.
(i) In the first case, one observes the so-called cage effect: at
short
times, any given particle is trapped in a confined area by its
neighbors
until the particle has managed to leave its cage and is able to
diffuse
through the sample by successive cage jumps [1]. Such features are
reminiscent of what is observed in colloidal suspension,
super-cooled
liquids or other glass formers, close to the glass transition. In
the
present case, we have shown that cage jumps organize in clusters
which
avalanche in a facilitation like process to build up long term
dynamical
heterogeneities [2,3].
(ii) In the second case, the quench protocol produces very dense
configurations with structural relaxation time much larger than the
experimental time scales. One observes that long-time correlations,
accompanied by the growth of spatial correlations are maximal at
a volume
fraction , where a snapshot of the displacement field reveals the
existence
of a super-diffusive motion organized in channel currents
meandering between
blobs of blocked particles [4,5].
We will discuss these results focusing on the distinction between
the glass
and jamming transitions also underlying the key role of friction
in granular
media as opposed to other glass formers.
\\[4pt]
[1] G. Marty, O. Dauchot, PRL 94, 015701 (2005).
\\[0pt]
[2] O. Dauchot, G. Marty, G. Biroli, PRL 95, 265701 (2005).
\\[0pt]
[3] R. Candelier, O. Dauchot, G. Biroli, arXiv 0811.0201.
\\[0pt]
[4] F. Lechenault, O. Dauchot, G. Biroli and J. P. Bouchaud, EPL,
83 46003
(2008).
\\[0pt]
[5] F. Lechenault, O. Dauchot, G. Biroli and J. P. Bouchaud, EPL,
83 46002
(2008).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.L8.3