Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Poster I

DY 24.45: Poster

Wednesday, March 28, 2007, 16:00–18:00, Poster D

Extension of the entropy fluctuation theorem to non-equilibrium phase transitions — •Axel Fingerle and Stephan Herminghaus — MPI for Dynamics and Self-Organization, Bunsenstr. 10, D-37073 Göttingen, Germany

The Gallavotti-Cohen fluctuation theorem [1] is one of the few exact results known for chaotic systems in non-equilibrium states. It predicts that the fluctuations Δ s_p of the phase space volume obey the symmetry relation P(Δ s_p) = exp(Δ s_p) P(−Δ s_p). We point out that for wet granular matter the assumption of time reversibility in the GCFT is not fulfilled and that the phase space volume is conserved, Δ s_p ≡ 0, so that the Gallavotti-Cohen entropy Δ s_p does not contribute to entropy production. We also show that the similar definition Δ s_E = lnP(Δ E)/ P(−Δ E), in terms of exchanged heat, Δ E, at oscillating walls is not linear in Δ E, so that the distribution P(Δ E) does not fulfill the symmetry relation, in contrast to observations [2,3] of dry granular matter with less statistics. Finally it is shown that this non-linearity is an instable branch of entropy as a function of energy, ∂ s / ∂ E < 0, which corresponds to the fluid-gas transition of wet granular matter [4].

[1] G. Gallavotti and E.G.D. Cohen, Phys. Rev. Lett. 74, 2694 (1995).

[2] K. Feitosa and N. Menon, Phys. Rev. Lett. 92, 164301 (2004).

[3] A. Puglisi, et al., Phys. Rev. Lett. 95, 110202 (2005).

[4] A. Fingerle, K. Röller and S. Herminghaus, submitted.