[MITgcm-support] Linear internal waves evolution under a free surface and a rigid lid.

[Fancer Lancer]

Hi Jean-Michel,

Thank you for the respond. In fact your last suggestion
(cg2dUseMinResSol=1) solved the problem. Thank you very much.

Sincerely,
-Sergey


On Tue, Dec 31, 2013 at 9:27 PM, Jean-Michel Campin <jmc at ocean.mit.edu>wrote:

> Hi Sergey,
>
> Did you try commenting out "tempImplVertAdv=.TRUE.," ?
> The thing is I am not sure how well the implicit vertical
> advection is doing with a highly non-linear advection scheme
> like tempAdvScheme=77,
>
> You could also try to set:
>  cg2dUseMinResSol=1,
> in 2nd namelist (PARM02) of the main parameter file "data".
> This can help to pick the cg2d solution corresponding to the
> minimum residual (instead of the last iteration solution when
> it does not converge). But I am not sure that this will help you
> since it's seems to be the 3-D solver that first shows some
> convergence problems.
>
> And happy new year to you !
> Cheers,
> Jean-Michel
>
> On Tue, Dec 31, 2013 at 07:44:35AM +0400, Fancer Lancer wrote:
> > Dear MITgcm,
> >
> > *First of all I want to wish everyone a happy new year, let all your
> plans
> > come successfully true, models converge, researches turn out well!*
> >
> > And here is my question.
> > I am trying to run a few setups of quasi-monochromatic internal waves in
> a
> > two-layers environment with very sharp transition layer. The target of
> the
> > experiments is to research a transformation process of linear internal
> > waves over a sharp bottom obstacle. The linearity of the waves means very
> > small amplitudes of the disturbances comparing with a depth. So to speak
> we
> > calculate a small amplitude quasi-sinusoidal internal waves on a tiny
> > pycnocline over a sharp bottom obstacle. Technically there is no
> pycnocline
> > at all, but the transition between two layers is sharp.
> > That setup converges only if I specify the free surface, in case of the
> > rigid lid the system suddenly blows up.The monitor output shows a small
> > fluctuation of rhsMax in the middle of calculations:
> >  cg2d: Sum(rhs),rhsMax =  -1.00649220260016E-04  2.80476672625558E-08
> >  cg3d: Sum(rhs),rhsMax =  -4.36678712900714E-03  2.73727850080651E-11
> >  cg2d: Sum(rhs),rhsMax =  -1.00473220760270E-04  2.80986212383509E-08
> >  *cg3d: Sum(rhs),rhsMax =  -1.02540856095068E-06  1.16576772289106E-07*
> >  cg2d: Sum(rhs),rhsMax =  -9.74440421204186E-05  2.81449166440040E-08
> >  cg3d: Sum(rhs),rhsMax =  -4.22056718404259E-03  2.75142884748998E-11
> >  cg2d: Sum(rhs),rhsMax =  -1.00470277023852E-04  2.81813454193756E-08
> >  cg3d: Sum(rhs),rhsMax =  -4.35243360164479E-03  2.75448882646779E-11
> > ...
> > And after several time-steps the model blows up:
> >  cg3d: Sum(rhs),rhsMax =  -2.95322925916202E-15  1.00918335046307E+15
> >  STOP GAD_IMPLICIT_R: error when solving 3-Diag problem
> > That doesn't happen if the free surface is specified. I didn't find any
> > problem with CFL, but a surface elevation turns to an enormous value
> during
> > the calculations:
> > (PID.TID 0000.0001) %MON dynstat_eta_max              =
> >  -1.6182199742936E+01
> > (PID.TID 0000.0001) %MON dynstat_eta_min              =
> >  -1.6182199808065E+01
> > ...
> > (PID.TID 0000.0001) %MON dynstat_eta_max              =
> >  -1.2229692791603E+01
> > (PID.TID 0000.0001) %MON dynstat_eta_min              =
> >  -1.2229692856491E+01
> > ...
> > ...
> > (PID.TID 0000.0001) %MON dynstat_eta_max              =
> >  -4.3612306317841E+04
> > (PID.TID 0000.0001) %MON dynstat_eta_min              =
> >  -4.3612307712367E+04
> >
> > I don't know how it affects my calculations, since the surface is blocked
> > by a rigid lid.
> > Could you please tell me what is wrong here and give some guide how to
> fix
> > the problem?
> > (data file is in attachment)
> >
> > Sincerely,
> > -Sergey
>
>
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> > MITgcm-support at mitgcm.org
> > http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
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