In this paper, we construct a more general Besov spacesḂ ,q r 1 ,r 2 ,r 3 and consider the global well-posedness of incompressible Navier-Stokes equations with small data ), which, as far as we know, has not been discussed in other papers. Moreover, the smoothing effect of the solution to Navier-Stokes equations is proved, which may have its own interest.
KEYWORDSglobal well-posedness, Navier-Stokes equations, smoothing effect t u + P(u · ∇u) − Δu = 0. It is easy to see that the entries of P(u · ∇u) are first order homogeneous Fourier multipliers applied to bilinear expressions.A huge literature study the well-posedness of the NS equation, for example, Danchin, 3 Frisch et al, 4 and Xin. 5 Kato 6 initiated the study of the NS equations by proving that the NS problem (*) is locally well-posed in L 3 and global well-posed if the initial data are small in L 3 . The method consists in applying a Banach fixed point theorem to the integral formulation of the equation and was generalized by Cannone et al 7 to Besov spaces of negative index of regularity. More precisely, they proved that if the initial data are small in the Besov spaceḂ −1+ N p p,∞ (for p < ∞), then there is a unique, global in time solution. The study 6790