Regensburg 2013 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 21: Granular Matter / Contact Dynamics

DY 21.3: Talk

Wednesday, March 13, 2013, 15:30–15:45, H47

A local view on sheared granular matter — Jean-François Métayer¹, Annika Döring¹, Song-Chuan Zhao¹, Mario Scheel², and •Matthias Schröter¹ — ¹Max Planck Institute for Dynamics and Self-Organization, Göttingen — ²ESRF, Grenoble, France

Whenever granular material flows along a stationary boundary, it is sheared. Examples reach from downhill avalanches to industrial hopper flows. Inside the shear flow, the volume fraction will change depending on the initial density; loose packings will compact when sheared, dense samples will expand. The transition between these two responses is called dilatancy onset. At present our understanding of it is still mostly phenomenological, e.g. there is no theory predicting the volume fraction of dilatancy onset as a function of friction, shape, or pressure.

This talk will present a local view of sheared sphere packings using fast X-ray tomography at the European Synchrotron Radiation Facility ESRF in Grenoble. While we find no scaling of the volume response with the contact number, as stipulated by the Jamming paradigm, we do see a dependence on the local volume fraction and the local strain rate.