[CIG-LONG] Conservation of Mass

[laetitia le pourhiet]

Louis,

I didn't get completely your message..

Is there a way or not in the current version of gale to get Q1P0 and/or 
Q2P1 working?
Or do you recommend using Q1P0 with UW?
if so, it would be very usefull to provide users with example files with 
the source of gale.

Laetitia

On 9/24/11 1:28 PM, Louis Moresi wrote:
> 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 <mailto: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
>>
>>
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>
>
>     -- 
>     *Dr Laetitia Le Pourhiet*<\n> MCF - Institut des Sciences de la
>     Terre Paris - UPMC<\n> tel : +33 1 44 27 58 83
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-- 
*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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