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Granular Imipact Dynamics: Grain scale to Macroscale

Abram Clark (Duke University), Robert Behringer ()

Multiscale Mechanics of Particulate Media

Mon 9:00 - 10:30

Sayles 105

Granular impact, where a high-speed intruder strikes a granular material, occurs frequently in industrial and natural processes. Due in part to difficulty in obtaining sufficiently fast data at the grain scale, a complete description, which connects grain-scale processes to macroscopic dynamics of the intruder, is still lacking. Using photoelastic particles and a high speed camera, we perform experiments which allow us to capture the intruder dynamics, particle flow-fields, and local granular force response at very fast time scales. This allows us to approach the problem both macroscopically, fitting the intruder dynamics to a fluid-like force law, and microscopically, where we observe large force fluctuations at small space and time scales. Analyzing both approaches gives insight into the connection between large and small scales, as well as the connection between local fluctuations and a continuum description for other granular flows.