_Re:_Re:_[MITgcm-support]_Advection_schemes
Patrick Heimbach
heimbach at MIT.EDU
Thu Aug 19 08:06:59 EDT 2004
Petter,
I have a suspicion, but not sure:
You mentioned the tr1 array. Are you using it?
This is a legacy array that was introduced for
just one passive tracer before the advent of the
multi-dim. advection scheme.
So you shouldn't be using that array anymore.
Instead, use the array pTracer defined in
pkg/ptracers/PTRACERS.h
But maybe you are doing this anyways...
-Patrick
Quoting Martin Losch <mlosch at awi-bremerhaven.de>:
> Petter,
> I am a little puzzled by your results, I have been using DST-3 with
> flux limiter (scheme 33) for quite some time now also with older
> checkpoints and (17) passive tracers (with the ptracers-pkg), and I
> haven't had any of your problems, yet. Let's not hope that you have
> discovered something that will make my last year's work worthless
> (don't worry, it's worthless anyway (o:)
>
> Another test: use a linear equation of state (eosType='LINEAR') and set
> sBeta=0., so that theta is basically density/buoyancy and salinity is
> passive. Then salinity and your explicit passive tracer should give the
> same results (provided that ptracers_forcing uses the salinity forcing,
> this is the default). In all of my experiments this was the case.
>
> Martin
>
> On Aug 19, 2004, at 12:20 AM, Petter Stenström wrote:
>
> > Hi Patrick,
> >
> > Thanks for your reply. Noop, I did not forget to specify
> > tracerAdvScheme=33. The problem seems rather to be that multiDimAdv
> > has to
> > be false when using scheme no 33. I looked again in the documentation
> > and
> > found a note on that.
> >
> > The strange thing is that this seems to be required only for tr1, not
> > for T
> > and S. I ran a simple experiment in a simple domain with exactly the
> > same
> > initial distribution and concentration of T and tr1, and the same
> > advection
> > scheme (33). tr1 goes to infinity, whereas T stays on realistic values.
> > Strange since tr1 seems to use the same diffusivity constants as T in
> > the
> > default configuration. I will look closer in the code and try to
> > figure out
> > what the difference between the two is.There are slight differences
> > also
> > when using other schemes (I've tried 3rd order upwind biased).
> >
> > /Petter
> >
> >
> >
> > ------- Original message -------
> > From: heimbach at MIT.EDU
> > Date: Wed, 18 Aug 2004 15:27:19 -0400
> >
> > Hi Petter,
> >
> > sorry I oversaw your reply
> > (I am CC-ing to mitgcm-support and suggest
> > that you always send to that list).
> >
> > Re. your question I think you forgot to also specify
> > tracerAdvScheme = 33
> > in your data file.
> > Can you try and see whether that gives the
> > desired results?
> >
> > -Patrick
> >
> >
> >
> > Quoting Petter StenstrXm <petters at kth.se>:
> >
> >> Hi Patrick,
> >>
> >> thanks. 33 is apparently a flux limited 3rd order DST. It works fine
> >> with
> > S
> >> and T, but not with a passive tracer. I cannot understand why, but
> >> false
> >> extrema appear in the TR1 field, but not in the S and T fields, when
> >> I use
> >> 33 for all of them. Is there an obvious explanation for this that I
> >> don't
> >> see?
> >>
> >> Petter
> >>
> >> ------- Original message -------
> >> From: heimbach at MIT.EDU
> >> Date: Tue, 17 Aug 2004 14:35:19 -0400
> >>
> >> Hi Petter,
> >>
> >> they are described in sections 2.16, 2.17
> >> http://mitgcm.org/sealion/online_documents/node71.html
> >> http://mitgcm.org/sealion/online_documents/node76.html
> >> of the online documentation,
> >> but for the actual number associated with each sheme
> >> you'll have to look in the header file
> >> pkg/generic_advdiff/GAD.h
> >>
> >> -Patrick
> >>
> >>
> >>
> >> Quoting Petter StenstrXm <petters at kth.se>:
> >>
> >>> Hi!
> >>>
> >>> Is there a list of all the different advection schemes available and
> > their
> >>> corresponding numbers? I cannot find any in the documentation.
> >>>
> >>> I have been using advection scheme 33 for some time (which I thought
> > was a
> >>> flux limiter scheme), but when I look now, I cannot see that the
> >>> value
> > 33
> >>> is interpreted anywhere in the code.
> >>>
> >>> Regards,
> >>>
> >>> Petter Stenström
> >>> Dept of Land and Water Res Eng
> >>> Royal Institute of Technology
> >>> SE-100 44 Stockholm
> >>> Phone: +46 8 7908657
> >>> Email: petters at kth.se
> >>>
> >>> _______________________________________________
> >>> MITgcm-support mailing list
> >>> MITgcm-support at mitgcm.org
> >>> http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
> >>>
> >>
> >>
> >> --------------------------------------------------------
> >> Patrick Heimbach Massachusetts Institute of Technology
> >> FON: +1/617/253-5259 EAPS, Room 54-1518
> >> FAX: +1/617/253-4464 77 Massachusetts Avenue
> >> mailto:heimbach at mit.edu Cambridge MA 02139
> >> http://www.mit.edu/~heimbach/ USA
> >>
> >>
> >>
> >>
> >
> >
> > --------------------------------------------------------
> > Patrick Heimbach Massachusetts Institute of Technology
> > FON: +1/617/253-5259 EAPS, Room 54-1518
> > FAX: +1/617/253-4464 77 Massachusetts Avenue
> > mailto:heimbach at mit.edu Cambridge MA 02139
> > http://www.mit.edu/~heimbach/ USA
> >
> >
> >
> > _______________________________________________
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> > MITgcm-support at mitgcm.org
> > http://dev.mitgcm.org/mailman/listinfo/mitgcm-support
>
>
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--------------------------------------------------------
Patrick Heimbach Massachusetts Institute of Technology
FON: +1/617/253-5259 EAPS, Room 54-1518
FAX: +1/617/253-4464 77 Massachusetts Avenue
mailto:heimbach at mit.edu Cambridge MA 02139
http://www.mit.edu/~heimbach/ USA
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