[MITgcm-support] Weird numerical noise leads to the model blowing up

[Fancer Lancer]

Hi Michael,
No, the model worked in the non-hydrostatic mode.
In addition there is the rigid lid on the surface.

Sincerely,
-Sergey


On Wed, Apr 9, 2014 at 5:58 PM, michael schaferkotter <
schaferk at bellsouth.net> wrote:

> were your experiments done in hydrostatic mode?
>
>
> On Apr 9, 2014, at 7:13 AM, Fancer Lancer wrote:
>
> > Good day MITgcmers,
> >
> > I use the linear potential theory to specify a small-amplitude internal
> wave in 2D case. I performed a lot of model runs for waves with different
> wavelengths for the various pycnocline depths. To cut it short most of them
> work pretty fine: initial wave propagates as it supposed to be predicted.
> But there are some experiments, which suddenly blow up with weird noise
> around the pycnocline (see the attached gif animated figure).
> >
> > Does someone know what is the possible reason of that strange behavior?
> >
> > It should be noted a few facts about the model setup:
> > 1) Since the linear theory is used to setup the velocity field the
> transition layer (pycnocline) between two water layers is supposed to be as
> thin as it possible. So ideally there shouldn't be the transition layer at
> all, but should be just the density jump. All the experiments work pretty
> fine even with the abrupt density jump (no pycnlocline), but some of them
> suddenly blow up (see the gif-figure).
> > 2) The linear theory implies that fluid interface perturbations should
> be infinitely small that's why I use the variable vertical resolution,
> which is huge around the fluid interface. But it should be noted, that I
> specify the corresponding time-step to satisfy the CFL condition and the
> most of the model runs work pretty well.
> >
> > Any suggestion concerning the problem would be appreciated.
> > Many thanks in advance.
> > Sincerely,
> > -Sergey
> >
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>
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