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

[Erik Schnetter]

Bernard

Maybe there is a change in the interpolation scheme used for the multipole
extraction? There may have been some changes regarding how buffer points
are treated.

-erik



On Fri, Nov 30, 2012 at 11:07 AM, Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY
OF MARYLAND BALTIMORE COUNTY] <bernard.j.kelly at nasa.gov> wrote:

> Hi Ian and others. Coming back to this unresolved issue ...
>
> I've looked at 1D metric files from a fairly advanced point in the
> evolution, and can see no differences in the metric components from the
> two evolutions. It's difficult to do precise differencing, since the grids
> are not commensurate, as pointed out before.
>
> More directly, I've looked at the WeylScal4 waveforms along the coordinate
> axes, and they show no sign of the amplitude discrepancy. Attached is the
> output from psi4 along the x-axis at around 120M in the evolution (Med
> resolution).
>
> So it looks like the change is in the Multipole extraction. Diffing the
> two Multipole thorns (and ignoring test-suite file changes), I only see
> minor changes in the schedule.ccl:
>
> 8c8
> < schedule Multipole_Calc at CCTK_ANALYSIS after (calc_np,PsiKadelia)
> ---
> > schedule Multipole_Calc at CCTK_ANALYSIS after
> >(calc_np,PsiKadelia,Accelerator_CopyBack)
>
>
> Again: has anyone run the Curie-era paper's "bbh" parameter files with a
> later release of ET and obtained *exactly* the same WF amplitudes? Or a
> difference within 1%?
>
> Bernard
>
> On 11/9/12 1:24 PM, "Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF MARYLAND
> BALTIMORE COUNTY]" <bernard.j.kelly at nasa.gov> wrote:
>
> >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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-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/
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