  In the present paper, we study the long time behaviour of the solutions of
the second grade fluids equations in dimension 3. Using scaling variables and
energy estimates in weighted Sobolev spaces, we describe the first order
asymptotic profiles of these solutions. In particular, we show that the
solutions of the second grade fluids equations converge to self-similar
solutions of the heat equations, which are explicit and depend on the initial
data. Since this phenomenon occurs also for the Navier-Stokes equations, it
shows that the fluids of second grade behave asymptotically like Newtonian
fluids.
