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@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@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@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@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/users