Defines incompressible Navier-Stokes problems as a special case of general elliptic systems.
Yields a quasi-Newton linearization of the term u . grad u which has the form a Re u0 . grad u + b Re u . grad u0 = (a + b - 1) Re u0 . grad u0 a and b are given by the values of the special variables *alpha* and *beta*.
The pressure and continuity part of the Navier-Stokes equation. These parts can be multiplied by factors eta and xi which can be useful for debugging, for example.