the same boundary conditions for vorticity in Section 2. We deal with operator curl in Section
3. We derive (or re-derive) some properties which we apply in the next sections. In Sections
4 and 5, we show that the basic theory of the Stokes and the Navier-Stokes equations can
be extended to the case of the boundary conditions (1.4). Finally, we treat some problems
whose solution is different with the boundary conditions (1.4) than with the classical non-slip …