Dresden 2014 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 43: Focus session: Slow Dynamics in Glasses and Granular Matter II (joint session DY/ CPP/ DF)
DY 43.5: Hauptvortrag
Freitag, 4. April 2014, 11:00–11:30, HÜL 186
A Granular Ratchet: Spontaneous Symmetry Breaking and Fluctuation Theorems in a Granular Gas — •Devaraj van der Meer1, Sylvain Joubaud2, Peter Eshuis1, Ko van der Weele3, and Detlef Lohse1 — 1University of Twente, The Netherlands — 2ENS and University of Lyon, France — 3University of Patras, Greece
We construct a ratchet of the Smoluchowski-Feynman type, consisting of four vanes that are allowed to rotate freely in a vibrofluidized granular gas. The necessary out-of-equilibrium environment is provided by the inelastically colliding grains, and the equally crucial symmetry breaking by applying a soft coating to one side of each vane. The onset of the ratchet effect occurs at a critical shaking strength via a smooth, continuous phase transition. For very strong shaking the vanes interact actively with the gas and a convection roll develops, sustaining the rotation of the vanes. From the experimental results we show that a steady state fluctuation relation holds for the work injected to the system, and that its entropy production satisfies a detailed fluctuation theorem. Surprisingly, we find that the above relations are satisfied to some extent even when a convection roll has developed and there exists a strong coupling between the motion of the vanes and the granular gas.