FW: [MITgcm-support] obcs for lock-exchange problem (fwd)

[Patrick Heimbach]

Hi Michael,

I've only partially followed this discussion,
so not sure what your latest status is.
3 things from my side:

- If you're using Orlanski and have a western OB, there's a bug in the code.
  I hope to check in a fixed version later today.

- If you prescribe and read in OB values, there's a bug in the
  mdsio_slice*.F routines, for multi-processor usage
  (works fine on 1 proc.)
  I've checked in fixed code 11 days ago.
  You may want to 
  cvs update mdsio_slice*

- A variant of the obcs package is not currently part of the MAIN
  MITgcm distribution. It handles 'real time' OB I/O and sponge layers,
  but some issues re. balancing the flow may need attention.
  We can provide this code, but it may need careful testing at your end.

Cheers
-Patrick

Quoting samar khatiwala <spk at ldeo.columbia.edu>:

> Hi Michael
> 
> Glad to hear you were able to get the OBC to work (at least partially).
> 
> > 2) cVelTimeScale
> >
> > after reading the code, it was determined that the filtering of the phase
> speed probably needed to be adjusted,so
> > setting cVelTimeScale closer to deltaT changed things such that the plumes
> go out the boundaries now.
> 
> Yes, in the absence of some intrinsic time scale in the problem, setting
> cVelTimeScale=deltaT may be your best bet. The Orlanski OB code was
> originally developed for wave problems where such a time scale is easier
> to identify.
> 
> > i/m still not clear as to exactly which OBCS schemes are available. any
> pointers?
> 
> Basically, you can have
> (1) a radiation BC - only Orlanski is implemented as far as I know
> (2) prescribed, including sponge, BC.
> 
> Also, there is a variant of (1) that only radiates the "wave" or variable
> part of the solution by first subtracting out a mean flow. This is
> probably not in the standard obcs package, but it exists if you are
> interested.
> 
> Samar
> 
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> 


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Patrick Heimbach       Massachusetts Institute of Technology
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