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Free shear zones in granular bulk flow

Friday 9th January 2009 - 14:25 to 14:50
INI Seminar Room 1
We study shear localisation of granular media in slow three-dimensional shear flows. We focus on free shear zones which arise in the bulk of the material far from the confining walls of the shear cell. Free shear zones have many remarkable properties. Eg, their shapes exhibit nontrivial open or closed forms found in modified Couette experiments, their widths show sublinear scaling with the system size, shear zones are refracted at material interfaces similarly to light refraction. The shear zones are investigated in quasi-static and stationary flows where the behaviour is very robust: there is no dependence on the driving rate or on the preparation history. Our goal is to learn more about the puzzling mechanism that sets the rheology in quasi-static shear flows. We analyse the inner structure, the deformation and stress field of shear zones based on computer simulations using a discrete element method. The behaviour is also discussed within the framework of a recent mesoscopic model of slow shear flows, where the smooth deformation profile is provided by a series of thin shear hands.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons