[MITgcm-support] Re: orlanski open boundary conditions

[samar khatiwala]

Hi Martin.

If you can provide more details of the actual OBC being applied, I may be
able to help. For instance, is there a mean flow in the problem? Do you
want to apply the OBC to the entire flow? Are you using ABII? With/out
nonlinear free surface?

One immediate suggestion I have is to check for volume conservation. I too
had a problem with domain averaged sea level not remaining constant.
(Another user had the same problem.)

Samar

On Tue, 2 Dec 2003, Martin Losch wrote:

> Hi,
>
> is there any experience on how well the open boudary conditions with
> orlanski radiation  are working? I would like to study the
> relaxation/spin-down of a solitary geostrophic eddy and from my initial
> adjustment I get all sorts of odd processes near the open boundaries
> (only "north" and "east"). I had hoped that the gravity waves would be
> more or less radiated out of the domain, which they mostly do, but
> there are strong vertical velocities near the open boundaries and
> eventually, the (linear free) sea-surface height is affected (its mean
> goes down by meters) and the solution diverges (explodes).
>
> Any experience with this? Any ideas?
>
> Martin
>
> PS. this is my data.obcs
>   &OBCS_PARM01
>   OB_Jnorth=100*-1,
>   OB_Jsouth=100*1,
>   OB_Ieast=100*-1,
>   OB_Iwest=100*1,
>   useOrlanskiNorth=.TRUE.,
>   useOrlanskiSouth=.TRUE.,
>   useOrlanskiEast =.TRUE.,
>   useOrlanskiWest =.TRUE.,
>   &
>
>   &OBCS_PARM02
>   cmax=0.45D0,
>   cvelTimeScale=500.D0,
>   &
>