FM 96-6 Author: Giovanni Gallavotti Title: Dynamical ensembles equivalence in fluid mechanics Abstract: Dissipative Euler and Navier Stokes equations are discussed with the aim of proposing several experiments apt to test the equivalence of dynamical ensembles and the chaotic hypothesis. Keywords: Strange attractors, Chaoticity principle, Fluid mechanics, Navier-Stokes equation Fisica, Universita' di Roma La Sapienza, P.le Moro 2, 00185, Roma, Italia. e-mail giovanni@ipparco.roma1.infn.it tel. 6-49914370, fax 6-4957697