[MITgcm-support] problem with free-slip boundary conditions

[pairaud]

Dear all,

We are currently trying to simulate a very simple two-dimensional flow,
with free-slip boundary conditions (this is a single vortex in a pi^2
domain, with constant background temperature). The problem is that we
are not able to impose free-slip conditions on all four boundaries.
Indeed, on the east and top boundaries, a non zero velocity component
appears normal to the boundary, which leads to a blow-up of the code
after a few iterations (everything is ok on the two other boundaries).
Here is what we use:

      in data :
          _ exactConserv=.FALSE.
          _ implicitFreeSurface=.FALSE.,
          _ rigidLid=.TRUE.,
          _ nonHydrostatic=.TRUE.,
          _ no_slip_sides=.FALSE.,
          _ no_slip_bottom=.FALSE.,

     in data.pkg :
          _ useOBCS   = .FALSE.,

     in OBCS_OPTIONS.h :
          _ #undef ALLOW_ORLANSKI
          (everything is #undef actually in this file).

Apparently something is missing because the flow behavior is incorrect
as just explained. We would very much appreciate getting your help about
this problem.

Regards,

Ivane