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Graduate Student Seminar - 11/04/2011

"The Path to Fracture in Granular Flows: Dynamics of Contact Networks"

by Mark Herrera

Friday, November 4, 2011 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor:  Professor Edward Ott

Capturing the dynamics of granular flows at intermediate length sales can often be difficult. We propose studying the dynamics of contact networks as a new tool to study fracture at intermediate scales. Using experimental 3D flow fields with particle scale resolution, we calculate the time-evolving broken-links network and find that a giant component of this network is formed as shear is applied to this system. We implement a model of link breakages where the probability of a link breaking is proportional to the average rate of longitudinal strain (elongation) in the direction of the edge and find that the model demonstrates qualitative agreement with the data when studying the onset of the giant component. We note, however, that the broken-links network formed in the model is less clustered than our empirical observations, indicating that the model reflects less localized breakage events and does not fully capture the dynamics of the granular flow.

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