Temperature and correlations in effective theories for driven dissipative systems
| When |
Nov 10, 2015
from 02:00 to 03:00 |
|---|---|
| Where | Centre Blaise Pascal |
| Attendees |
Giacomo Gradenigo |
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The meaning of "effective temperature" for dissipative systems is a controversial issue in out-of-equilibrium statistical mechanics. I review here two examples where the interplay between effective temperature variations and ordering properties of the system can be understood.
First, I discuss how the energy injection mechanism in a quasi 2D granular fluid can be effectively modeled as the action of an equilibrium thermostat, supporting this conjecture with numerical and experimental data. It turns out that correlations in the system grow with the "distance from equilibrium", i.e. the difference $T_b - T_g$ between the temperature of the thermostat $T_b$ and the kinetic temperature of the grains $T_g$. Second, I show how an effective "equilibrium-like" theory, inspired by the Edwards theory for amorphous packing of frictional grains, provides a very good description for a driven spring-block model where the sliding of blocks on the horizontal plane is subjected to Coulomb dry friction. Theoretical predictions are compared with simulations, allowing us to point out the existence of a critical point at infinte effective temperature.