[MITgcm-support] OBCs over topography!

[Matthew Mazloff]

Hi Van Thinh!

You can give all cells and the masks will take care of it.  (e.g.  
OB_Ieast=80*-1,OB_Iwest=80*1 is fine)

Other things I have learned:
1) You should make the topogrophy flat right at the obcs.  (e.g. make 
the height at (i,j) = (i+1,j) for the western boundary)
2) Do not use the CD scheme with obcs

-Matt


Van Thinh Nguyen wrote:

>Hi
>
>I'm confused how to set up the boundary condition at a OB where a
>topography intersects with the grid block (please see my figure enclosed).
>I would like to simulate internal waves due to a tidal flow over a
>depression Gaussian bump in a channel, which has OBCs at West and East,
>North & South are closed sides. It looks like the geometry in exp4, the
>difference is only the bump (my case is depression bump!).
>Model is 3D, but the Fig. enclosed is a (X,Z) section at middle of bump.
>
>At West/East OBs, topography intersects grid block at cell 55 (Z direction
>with 80 cells). It means:
>
>- from free surface to cell 55 is OB
>- from cell 55 to the bottom is closed
>
>In this case, should I define cells (1-55) are OBCs in data.obcs or I can
>define all cells at West/East are OBCs (with OB_Ieast=80*-1,
>OB_Iwest=80*1)
>
>
>Could someone please give a hint for this?
>
>Thanks so much!
>
>Van Thinh
>
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