Tri-séminaire de Physique Statistique : Matthieu Wyart

Marginal stability and flow in granular materials

Matthieu WYART (New York University)

Complex systems are characterized by an abundance of meta-stable states.This is the case for granular materials, that can flow until one jammed configuration (among the exponentially many possible ones) is reached. I will argue that at least in popular simplified models of granular materials, these dynamically-accessible configurations are stable, but barely so. Such marginal stability offers a new perspective on both the solid and the liquid phase. I will discuss dense suspensions and propose to describe flow as a gas of elementary excitations, corresponding to the opening and closing of contact between particles. This approach leads to a detailed scaling description of rheological properties and length scales of dense flows. If time permits I will discuss a classification of athermal glassy systems based on the stability of low-energy excitations.


Date/Time : 02/07/2015 - 14:30 - 16:00

Location : LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay

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