Discontinuous shear thickening : dynamic jamming transition of frictional particles.
Mardi 12 novembre 2013
à 11h en salle C. Brot
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. Our model allows contacts between particles, assuming a breakdown of lubrication for a small interparticle gap. These contacts are treated with a model borrowed from granular physics. 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 a possible kinetic mechanism which differentiates Discontinuous and Continuous Shear Thickening.
Fluides & Matériaux Complexes
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