[CIG-LONG] CIG-LONG Digest, Vol 58, Issue 4

[Brian Wilson]

Thanks everyone for your suggestions; I will try adding the hydrostatic term
and using Q1P0 elements. Is there a way to set the element to Q1P0 in the
code or do I just need to use an earlier version? I'll look forward to using
Q2P1 elements too; hopefully things will run better when that is fully
implemented.

Regarding documentation, I didn't realize Underworld had it's own
documentation until now; I'll look through that as well. Maybe Underworld
user manual could be posted on the Gale page (
http://geodynamics.org/cig/software/gale)?

Cheers,
Brian

On Sat, Sep 24, 2011 at 1:00 PM, <cig-long-request at geodynamics.org> wrote:

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> Today's Topics:
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>   1. Re: Conservation of Mass (Louis Moresi)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 24 Sep 2011 21:28:10 +1000
> From: Louis Moresi <louis.moresi at monash.edu>
> Subject: Re: [CIG-LONG] Conservation of Mass
> To: laetitia le pourhiet <laetitia.le_pourhiet at upmc.fr>
> Cc: cig-long at geodynamics.org
> Message-ID:
>        <CACRTXu1Rpa=kG3OqLY574KWyqi9H7+J594w9yug+h-U3MzKJeA at mail.gmail.com
> >
> Content-Type: text/plain; charset="utf-8"
>
> For your information cig-long readers, Walter, Louise and I had a
> conversation around this issue two weeks ago.
>
> I don't think there are any supporters of Q1Q1 for this particular problem
> left any more. Underworld defaults to Q1P0 but provides recovered
> deviatoric
> stress and pressure quantities which mitigate the checkerboard problem.
> This
> can be configured quickly and is at least well-understood and tested.
>
> Q2P1 would be useful to have next. It is implemented in underworld (and
> therefore gale) but there are some shortcomings / bugs left to iron out
> with
> the current integration scheme for PIC and (my guess is that) there are
> some
> outstanding issues with multigrid and some of the processing plugins. I am
> not sure about the implementation of the stress / pressure recovery for
> these elements although they are likely to be less important.
>
> Walter was very keen to get this particular element working in gale before
> he steps back from active development.
>
> Louis
>
>
> On Sat, Sep 24, 2011 at 20:16, laetitia le pourhiet <
> laetitia.le_pourhiet at upmc.fr> wrote:
>
> >  Hi Brian and the others,
> >
> > There is not much you can do about that I gave up trying to do such
> models
> > with Gale.
> > It is now established Q1Q1 elements are not suited for this kind of
> > problems.
> > What you can do is  to
> > 1) Remove the free surface/sky to work with delta rho instead of rho
> > 2) Increase the resolution.
> >
> > Basically you should only use these elements for extended thin shit
> > problems.
> >
> > The old Q1P0 had other problems, but they could be used to model
> > drip/subduction problems.
> >
> > If CIG still wants to spend some time/money on Gale
> > It would be usefull to have a switch between elements, like in UW so that
> > depending on the model set up we can choose the best suited element.
> >
> > hope this was helpfull
> >
> > Laetitia
> >
> >
> > On 9/24/11 12:44 AM, Brian Wilson wrote:
> >
> > Hi all,
> >
> > I'm working on a model of lithospheric drip and despite having zero flux
> on
> > the boundaries, I am getting downward velocities with no compensating
> > upwelling, which would seem to violate the divergence free condition. Has
> > anybody else had a similar problem and/or figured out a solution? I've
> > attached a copy of my input file if anyone wants to look at it;
> everything
> > is scaled as follows: distance: km, mass: 10^15 kg, time: m.y.
> >
> > Thanks,
> > Brian
> >
> >
> > _______________________________________________
> > CIG-LONG mailing listCIG-LONG at geodynamics.orghttp://
> geodynamics.org/cgi-bin/mailman/listinfo/cig-long
> >
> >
> >
> > --
> > *Dr Laetitia Le Pourhiet*<\n> MCF - Institut des Sciences de la Terre
> > Paris - UPMC<\n> tel : +33 1 44 27 58 83<\n> web :
> > http://perso.numericable.com/laetitia.le.pourhiet/index.html<\n>
> >
> > _______________________________________________
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> > CIG-LONG at geodynamics.org
> > http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
> >
> >
>
>
> --
> ------------------------------
> <
> http://picasaweb.google.com/lh/photo/gQ7_To7dX8sI0sEe2ty0AaO6j9vpN3ZPghWjdy2iDOg?feat=embedwebsite
> >Professor
> LouisMoresi
> louis.moresi at monash.edu
> GoogleProfile <http://www.google.com/profiles/louis.moresi> | Busy or
> not ?<http://www.moresi.info/pages/lm-calendar>
> Underworld Geodynamics Software <http://www.underworldproject.org/>
> Mobile phone: +61 4 2850 1907 ?
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