Our objective in this article is to present some numerical schemes for the
approximation of the 2-D Navier-Stokes equations with periodic boundary con
ditions, and to study the stability and convergence of the schemes. Spatial
discretization can be performed by either the spectral Galerkin method or
the optimum spectral non-linear Galerkin method; time discretization is don
e by the Euler scheme and a two-step scheme. Our results show that under th
e same convergence rate the optimum spectral non-linear Galerkin method is
superior to the usual Galerkin methods. Finally, numerical example is provi
ded and supports our results. Copyright (C) 2001 John Wiley & Sons, Ltd.