On the extension to slip boundary conditions of a Bae and Choe   regularity criterion for the Navier-Stokes equations. The half-space case
  This notes concern the sufficient conditions for regularity of solutions to the evolution Navier-Stokes equations known in the literature as Prodi-Serrin's condition. H.-O. Bae and H.-J. Choe proved in a 1999 paper that, in the whole space R^3, it is merely sufficient that two components of the velocity satisfy the above condition. Below, we extend the result to the half-space case R^n_+ under slip boundary conditions. We show that it is sufficient that the velocity component parallel to the boundary enjoys the above condition. Flat boundary geometry seems not essential, as suggested by some preliminary calculations in cylindrical domains. 
Hugo Beirao da Veiga
math.AP