[MITgcm-support] changing deltaT based on CFL criterion

fancer fancer fancer.lancer at gmail.com
Mon Dec 26 11:36:23 EST 2011

Hi Jody,

I did not develop this feature, but I guess it is very useful. In my
opinion this workaround should be optional, for example it can be switched
in data file using bool variable: deltaTCFLCorrection={true,false}.
In fact I don't see critical obstacles for such feature implementing.
In addition MITgcm user needs to know when this procedure changes the
deltaT variabe. Therefore these changes must be reflected using one of the

Sergey Semin
PHD student
department of Applied Mathematics
NSTU named after R.E.Alekseev
Nizhniy Novgorod, Russia

On Sat, Dec 24, 2011 at 2:22 AM, Jody Klymak <jklymak at uvic.ca> wrote:

> Hi all,
> I *often* change grid sizes, forcings etc, and end up having to adjust
> deltaT to optimize it for my particular setup. This seems somewhat of a
> shame, because the problem is almost always the CFL criterion drifting
> slowly towards one somewhere, usually perfectly legitimately.
> In other models, I've hacked the code to simply halve deltaT if this
> starts happening, and set some acceptable lower bound that I kill the model
> on if.
> Is this possible with the MITgcm?  Issues I can see are
> 1) there are a few deltaT's kicking around
> 2) the mds output system seems to be based on model time, but the files
> are named based on number of timesteps.
> Has anyone done this?  Is it a bad idea?
> Thanks,   Jody
> --
> Jody Klymak
> http://web.uvic.ca/~jklymak/
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support
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