[MITgcm-support] problems at tile bdys?

[Yuan Lian]

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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