  Incompressible fluid equations are studied with UV cut-off and in periodic
boundary conditions. Properties of the resulting ODEs holding uniformly in the
cut-off are considered and, in particular, are conjectured to be equivalent to
properties of other time reversible equations. Reversible equations with the
same regularization and describing equivalently the fluid, and the fluctuations
of large classes of observables, are examined in the context of the "Chaotic
Hypothesis", "Axiom C" and the "Fluctuation Theorem".
