We study the tridimensional Navier-Stokes equations, written in a domain wh
ich is invariant under rotation around the vertical axis, or in the whole s
pace R-3; the solutions seeked are also invariant by that rotation, and we
look for conditions on the initial data which are close to the natural assu
mptions in the case of two space dimensions. (C) 2000 Academie des sciences
/Editions scientifiques et medicales Elsevier SAS.