Ja n 20 20 1 Equivalent Ensembles , Turbulence and Fluctuation Theorem

Stationary states of Navier-Stokes fluids have been proposed to be described equivalently by several alternative equations, besides the NS equation itself. In particular equivalence between the NS evolution and a reversible. It is natural to test whether, assuming the Chaotic Hypothesis, the Fluctuation Theorem can be applied to the reversible flows. Here an example is provided which also leads to the possibility of testing the prediction of the fluctuation theorem even in systems evolving irreversibly. I. ENSEMBLES AND NONEQUILIBRIUM