[Users] weird behavior with some ET simulations
Haas, Roland
rhaas at illinois.edu
Thu Mar 7 07:41:12 CST 2019
Hello Toni,
I am not sure about all the options that arpetRegrid2 offers.
The one that most likely helps is:
CarpetRegrid2::min_fraction = 1.0
which prevents CarpetRegrid2 from ever combining regions.
Yours,
Roland
> Hi,
>
> Roland you are right it is forming and destroying a common box each time
> the outburst of noise happens. Do you know how one could get rid of this
> noise, or if there are some parameters of Carpet which one could add to
> the parameter file to avoid such a behaviour?
>
> Thanks,
> Toni.
>
> El jue., 7 mar. 2019 a las 3:25, Haas, Roland (<rhaas at illinois.edu>)
> escribió:
>
> > Hello all,
> >
> > as Zach said, there have been updates to Carpet since then. Though the
> > behaviour is a bit odd.
> >
> > Carpet will merge refined boxes (eg the two boxes tracking the black
> > holes) if they overlap and form a single large enclosing box. This can
> > lead to a situation where, when the boxes are aligned in x or y, the do
> > not overlap but do when eg they are at 45 degree angels (since they
> > their corners overlap) eg:
> >
> >
> > xxxxxxxxxxxx ++++++++++++
> > x x + +
> > x x + +
> > x x + +
> > x x + +
> > xxxxxxxxxxxx ++++++++++++
> >
> > where everything is fine, vs:
> >
> > xxxxxxxxxxxx
> > x x
> > x x
> > x x
> > x ++++++++++++
> > xxxxxxxxxx+x +
> > + +
> > + +
> > + +
> > ++++++++++++
> >
> > where there is overlap and Carpet will make one large box like so:
> >
> > **********************
> > * x *
> > * x *
> > * x *
> > * +++++++++++*
> > *xxxxxxxxx+x *
> > * + *
> > * + *
> > * + *
> > **********************
> >
> > that encloses both black holes.
> >
> > You will be easily able to see this if you have 2d or 3d output, the
> > load it into eg VisIt, create a slice in the xy plane, then add a
> > "Mesh" plot.
> >
> > Similar effects can happen if the outer corner of one of the moving
> > boxes (think in 3d here, the outer edge is not on the xy plane but off
> > the xy plane by the height of the moving box) intersects with the
> > inner_sphere radius of Llama.
> >
> > Right now this is just guess but may expain the observed behaviour if
> > each of the bursts you saw is due to a bit of grid being created or
> > destroyed.
> >
> > Yours,
> > Roland
> >
> > > Hi Toni,
> > >
> > > The problem you report seems to be related to the AMR, which is a
> > > separate module from Llama. There have been multiple updates to the
> > > AMR infrastructure since 2017.
> > >
> > > -Zach
> > >
> > > * * *
> > > Zachariah Etienne
> > > Assistant Professor of Mathematics
> > > West Virginia University
> > > *https://math.wvu.edu/~zetienne/ <https://math.wvu.edu/~zetienne/>*
> > > https://blackholesathome.net
> > >
> > >
> > > On Wed, Mar 6, 2019 at 1:42 PM Antoni Ramos Buades <
> > > antoniramosbuades at gmail.com> wrote:
> > >
> > > > Hi,
> > > >
> > > > we are using a version of the EinsteinToolkit of 2017, particularly,
> > > >
> > > > !DEFINE ET_RELEASE = ET_2017_06
> > > >
> > > > so it is not one of the newest versions, but as far as I know in
> > > > the last releases there has not been updates on the Llama thorn.
> > > > Although we can try to run with older or newer versions if you
> > > > think it can help to solve the problem.
> > > >
> > > > Best Regards,
> > > > Toni.
> > > >
> > > >
> > > > El mié., 6 mar. 2019 a las 18:29, Zach Etienne
> > > > (<zachetie at gmail.com>) escribió:
> > > >
> > > >> Hi Antoni,
> > > >>
> > > >> This is a worrisome finding, thanks for sharing. It would be
> > > >> useful if you would let us know what version of the ET you are
> > > >> using. Further, if you could attempt the simulation with earlier
> > > >> versions of the ET (e.g., the first version with Llama included),
> > > >> it would help to determine if this issue arose due to some recent
> > > >> commit.
> > > >>
> > > >> -Zach
> > > >>
> > > >> * * *
> > > >> Zachariah Etienne
> > > >> Assistant Professor of Mathematics
> > > >> West Virginia University
> > > >> *https://math.wvu.edu/~zetienne/ <https://math.wvu.edu/~zetienne/>*
> > > >> https://blackholesathome.net
> > > >>
> > > >>
> > > >> On Wed, Mar 6, 2019 at 9:40 AM Antoni Ramos Buades <
> > > >> antoniramosbuades at gmail.com> wrote:
> > > >>
> > > >>> Hi,
> > > >>>
> > > >>> my name is Antoni Ramos Buades, I am PhD student in the
> > > >>> University of the Balearic Islands working with Sascha Husa. We
> > > >>> have been using ET with the Llama thorn to produce waveforms. We
> > > >>> have observed in some simulations strange behaviors in the
> > > >>> waveforms. For example, I have attached a plot of the amplitude
> > > >>> of the psi4 of a non-spinning q1 simulation, for different higher
> > > >>> order modes, where you can see that the 22, 32 and 44 show weird
> > > >>> spikes. We have rerun this simulation outputting 2D data in the
> > > >>> x-y plane. We have plotted the Hamiltonian constraint and made a
> > > >>> movie (I cannot attach the movie because its size is 42Mb ) but I
> > > >>> can attach some snapshots where you can observe that there seems
> > > >>> to be an outburst of noise when the boxes are aligned, and this
> > > >>> continues happening in the simulation each time the boxes are
> > > >>> aligned with each other. Geraint Pratten is also investigating
> > > >>> this issue adding some new parameters in the parameter file
> > > >>> (attached to the email) for the carpet mesh refinement like
> > > >>> freeze_unaligned_parent_levels, freeze_unaligned_levels, ... and
> > > >>> running some tests.
> > > >>>
> > > >>> We would like to ask you if somebidy has ever seen this thing
> > > >>> happening before and if somebody knows how one could solve this
> > > >>> problem, because with the same Carpet settings we have observed
> > > >>> that for some configurations (mass ratio and spins) this does not
> > > >>> happen, but for others, like the one presented in this email we
> > > >>> do. I have additional quantities as a 2D output like the
> > > >>> curvature, metric, horizon, ... in case you think they could be
> > > >>> used to check something.
> > > >>>
> > > >>> Thanks and best regards,
> > > >>> Toni.
> > > >>> _______________________________________________
> > > >>> Users mailing list
> > > >>> Users at einsteintoolkit.org
> > > >>> http://lists.einsteintoolkit.org/mailman/listinfo/users
> > > >>>
> > > >>
> >
> >
> >
> > --
> > My email is as private as my paper mail. I therefore support encrypting
> > and signing email messages. Get my PGP key from http://pgp.mit.edu .
> >
--
My email is as private as my paper mail. I therefore support encrypting
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