Science / Technology - Colloquium
Monday, October 30, 2006
4:00 PM-5:00 PM
Olin Hall
107
Materials as diverse as molecular liquids, foams and granular matter experience a transition from a fluid-like state to a solid-like state characterized only by a sudden arrest of their dynamics. These sudden arrests are difficult to predict and lead to catastrophic events such as the buckling of grain silos. Numerous experiments and simulations indicate the appearance of large-scale dynamical heterogeneities and an associated growing dynamical length scale. In colloids near the glass transition, for example, fast-moving particles were observed to be spatially correlated with a characteristic cluster size that increased as the glass transition was approached. In granular materials, spatial structures have been directly observed in experiments on flowing systems. Several questions naturally arise: (1) Are dynamical heterogeneities a necessary precursor to dynamical arrest of the jamming kind? (2) Do these heterogeneities and their mesoscopic scale lead to any kind of universal dynamical behavior irrespective of significant differences in microscopic dynamics? (3) Do static structures such as force chains observed in jammed granular packings emerge out of dynamical heterogeneities? In this talk I will address these questions through the analysis of a simple model that focuses on the essential effects of driving and dissipation in a flowing granular system.
Cost: FREE
Sponsored by: physics Dept., Dr. Stephen Jasperson
Suggested Audiences: College
E-mail:
snj@wpi.edu
Phone: 508-831-5392
Last Modified: October 20, 2006 at 3:17 PM
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