The fluid is modeled by the two dimensional incompressible
steady state Navier Stokes equations.
The fluid is described by its velocity vector **u**
(the first component is the horizontal velocity,
the second component denotes the vertical velocity) and
by its pressure *p*. The vector **b**
denotes given boundary velocities and **g**
is the top velocity to be determined.

In the following, variables set in boldface are vector valued.