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25 octobre 2013 : Ryohei Seto

par Claudine Lylap - 20 septembre 2013

Ryohei Seto

Laboratoire : Levich Institute, Steinman Hall #1M City College of CUNY 160 Convent Avenue New York, NY 10031 Téléphone : +1-212-650-8898 Courriel : http://www-levich.engr.ccny.cuny.ed...

Titre présentation : Discontinuous shear thickening as a dynamic jamming transition of frictional particles

Date de la présentation : Vendredi 25 Octobre

Lieu de la présentation : Rassat Heures de la présentation : 10h-12h Résumé de la présentation : Abstract The Discontinuous Shear Thickening observed in many dense athermal suspensions has proven difficult to understand and to reproduce numerically in the framework of pure hydrodynamics. The standard models, treating close interactions between particles as being dominated by lubrication, do not capture the abrupt shear rate dependence of the viscosity. Moreover, they miss the dependence on the nature of the suspended particles, in particular their surface friction. In this work, we propose a new simulation model including contact and hydrodynamic forces. We use a simplified lubrication model including leading terms of the squeeze and tangential modes of pair-wise hydrodynamic interaction. Our model allows contacts between particles, assuming a breakdown of lubrication for a small interparticle gap. These contacts are treated with a frictional contact model, which is adapted for a system of particles immersed in a fluid. The overdamped inertia-free dynamics is determined by solving the force and torque balance equations. It exhibits an abrupt shear thickening and recovers the experimentally observed dependence on friction coefficient and volume fraction. Within this framework, we describe the discontinuous shear thickening as a dynamic jamming transition, showing a characteristic structural signature. We also discuss its relation to the static jamming transition of granular matter.

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