[Users] **large** amplitude changes in WFs from Curie "bbh" parfiles when run in ET_2012_05

[Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF MARYLAND BALTIMORE COUNTY]]

Hi Ian. Thanks for the diagnostic suggestions.


On 11/7/12 3:59 PM, "Ian Hinder" <ian.hinder at aei.mpg.de> wrote:

>
>On 7 Nov 2012, at 20:29, "Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF
>MARYLAND BALTIMORE COUNTY]" <bernard.j.kelly at nasa.gov> wrote:
>
>> Hi. This may be related to something Yosef brought up back in July
>> ["Differences in results ..." from 26 July], but I'm seeing sizable
>> differences in WF amplitudes from Multipole when running the parameter
>> files for the ETK paper (Loeffler et al.).
>> 
>> Specifically, if I take the parameter file
>> 
>> <Cactus>/par/arXiv:1111.3344/bbh/BBHMedHRes.par
>> 
>> ... and run it with a Curie (ET_2011_05) executable, my r=30M (2,2) mode
>> has a peak magnitude of just above 0.0027. Rerunning the same parameter
>> file with *no* changes, using the current release, Lovelace
>>(ET_2012_05),
>> the same peak amplitude is just above 0.00257 -- a drop of almost 5%.
>> 
>> Can anyone tell me what might be going wrong? Is there some kind of
>>change
>> in default dissipation that could explain such a large discrepancy?
>
>I don't think so.  McLachlan with its default parameters has always
>disabled dissipation.  We changed the default of apply_dissipation very
>recently (i.e. after Lovelace) from "true" to "false" (and announced this
>on the list), but the dissipation strength has always defaulted to zero.
>
>Dissipation in that parameter file is provided by the Dissipation thorn,
>and it uses its default value of epsdiss = 0.2.
>
>Could this be related to the change in grid structure going from the
>"git" to the "mercurial" version of Carpet?  Are the grid structures the
>same? You can output the grid structure to an ASCII file using
>
>	Carpet::grid_coordinates_filename       = "carpet-grid.asc"

I'm attaching some excerpts from the carpet-grid-coordinates files of both
runs ("MedRes" version). They're snapshots from iterations 0, 609, and
2145. For the latter two iterations, the grid does seem to be different in
the y-direction (the only direction without a symmetry boundary), but only
for certain refinement levels. The it=0 output is very different for the
two cases; I'm not sure why.

Also, the Curie executable generated this diagnostic information *far*
more frequently (every 32 iterations) than Lovelace (every 384).
Obviously, the times I've chosen were common to both.

>
>Can you try to narrow down where the differences lie?  For example, you
>could look at the grid functions themselves, including one of the evolved
>variables, one of the ADMBase variables, and also Psi4, to see which are
>actually different.

I'll look at the 1D grid functions now, but I wanted to get you this info
anyway.

Bernard

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