[MITgcm-support] problems at tile bdys?

[Jody Klymak]

Hi Jean-Michel,

Here is mine.  

In the meantime I'll work on a more minimal example.  

While I use obcs, note that my obcs boundary conditions are basically zero forcing for the first 1200 time steps of the model, so this shouldn't cause a problem.  And, of course, the exact same set up works with 64 cores instead of 128.

Thanks,   Jody

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On Jun 17, 2013, at  5:41 AM, Jean-Michel Campin <jmc at ocean.mit.edu> wrote:

> Hi Yuan,
> 
> Could you proceed with the same recommendation (sending tar file of dir with 
> modified/customized source file and all data* files for this set-up)
> or is there too much source-code involved ?
> 
> If we are lucky, it could be the same Pb and then will be easier to identify 
> with 2 set-up (instead of just 1). Otherwise, might have 2 separate Pb to fix ...
> 
> Cheers,
> Jean-Michel
> 
> On Sun, Jun 16, 2013 at 09:35:08PM -0700, Yuan Lian wrote:
>> Hi Jean-Michel,
>> 
>> I found the similar behavior of MITgcm when there are multiple tiles in x direction. The issue is particularly obvious when active tracers are enabled, e.g. water cycle, where I can see the periodical oscillation of tracers including temperature at the boundaries between the tiles. The problem is less apparent in y direction. I am wondering if it has something to do with exchange routines in x direction. The simulations are done in 3d channel. Thanks.
>> 
>> Best,
>> Yuan 
>> 
>> Jean-Michel Campin <jmc at ocean.mit.edu> wrote:
>> 
>>> Hi Jody,
>>> 
>>> Could you send (in a tar file) the directory that contains all the 
>>> modified/customized files you are using (the argument of "genmake2
>>> -mods" command)
>>> as well as all the parameter files (all data* files) for this set-up ?
>>> Also, if you are not using the latest version of MITgcm code, which
>>> version 
>>> (checkpointXYz ? or time of the latest "cvs update") are you using ?
>>> 
>>> It's possible that we can find the problem like this; otherwise, will
>>> have 
>>> to try to reproduce it (and in this case will also need the binary
>>> input files).
>>> 
>>> Cheers,
>>> Jean-Michel
>>> 
>>> On Sat, Jun 15, 2013 at 11:03:30PM -0700, Jody Klymak wrote:
>>>> 
>>>> Hi All,
>>>> 
>>>> I ran a simulation in a 2-D channel but three-D in setup, and all ran
>>> fine.  Well except it stayed 2-D because there was nothing to cause
>>> there to be spanwise motion.  The simulations are nonhydrostatic.  
>>>> 
>>>> So, I added a very small amount of three d by a few different
>>> methods, and everytime, no matter how I set up the three dimensionality
>>> (bottom roughness, initial velocities, surface displacements) there
>>> would an instability at the same spot in x.  It turns out it is a tile
>>> boundary in the middle of the domain.  
>>>> 
>>>> I'm using advection scheme 33, and chnaged OLx and OLy to 5, but
>>> still the same problem.  I tried a few other advection schemes, with
>>> the same issue (it happens in a hundred or so timesteps, so its easy to
>>> debug, at least).  I also tried upping the iterations on the CG3d
>>> solver, but that didn't help at all.
>>>> 
>>>> I've now gone back to the same setup I started with, but changed by
>>> tile layout (half as many tiles), and the instability is gone.  
>>>> 
>>>> Has anybody run into this?  Any suggestions for a fix or what to look
>>> for?  (I guess the stupid fix is not to use that tile configuration,
>>> but that seems flakey).
>>>> 
>>>> Thanks,   Jody
>>>> 
>>>> 
>>>> --
>>>> Jody Klymak    
>>>> http://web.uvic.ca/~jklymak/
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
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>>> 
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>> 
>> -- 
>> Sent from my Android phone with K-9 Mail. Please excuse my brevity.
> 
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--
Jody Klymak    
http://web.uvic.ca/~jklymak/