Hello,

Regarding the Binary Black Hole coalescence example from the ETK.

In the BH diagnostics files are columns with quadrupole terms, which
are not constant. Do you know of some tool in ETK to calculate the GW
emission from these terms?

Thanks,
Jose

On Tue, Jan 17, 2012 at 5:18 AM, Ian Hinder <ian.hinder@aei.mpg.de> wrote:

On 17 Jan 2012, at 13:37, Jose Fiestas Iquira wrote:

The Einstein Analysis guide is very useful. I found here

http://einsteintoolkit.org/documentation/ThornGuide/ThornGuidech142.html#x159-2520000P8.4

the units used in 'Hydrobase'.

If I assume these are the units for all thorns, I obtain from data in

BH_diagnostics.ah1.gp a unit of distance of about 1 Km. To estimate

the time I am using a mass of ~0.5 M_sun for both BHs (m_irreducible

?) , and I read a final time (cctk_time) ~ 1microsec. Are these

quantities in the usual range?

The length unit is G M / c^2 and the time unit is G M / c^3.  For M = M_sun,

I get the length unit as 1.5 km and the time unit as 4.9 us.  The final time

in the simulation is 100 M (i.e. 100 G M / c^3), which would be 0.5 ms.

Jose

On Tue, Jan 17, 2012 at 4:04 AM, Jose Fiestas Iquira <jafiestas@lbl.gov>

wrote:

I sent the wrong file, here is the right one.

$ hg tip

 gives me:

-----------------------------------------------------

changeset:   3421:dff4df2b3687

tag:         tip

user:        Erik Schnetter <schnetter@cct.lsu.edu>

date:        Thu Jan 12 14:11:27 2012 -0500

summary:     CarpetLib: Allocate space for dstbox before

restricting/prolongating

[40514 refs]

-----------------------------------------------------

I copied this version from:

./GetComponents -a

http://svn.einsteintoolkit.org/manifest/trunk/einsteintoolkit.th

Thanks,

Jose

On Tue, Jan 17, 2012 at 1:13 AM, Ian Hinder <ian.hinder@aei.mpg.de> wrote:

On 16 Jan 2012, at 23:21, Jose Fiestas Iquira wrote:

Thanks, I am attaching the output file.

The output file looks fine - I can't see any problem with the simulation.

 According to the output file, it reached t = 100 M, and in the parameter

file that is listed as cctk_final_time, so all looks well!

I did copy the development version. As I can see, it was already

fixed, so I should not get this warning, since I copied the

development version.

Yes, if you are using the current development version, then I don't know why

you get the warning.  Can you check which version of Carpet you have by

doing

cd repos/carpet

hg tip

to be sure you are using the development version?

Is  the puncture tracker not a better way to plot BH trajectories.

It's cheaper to use the puncture tracker, because computing the horizon

centroid is more expensive, but it has to be done every iteration, whereas

the horizon can be found less frequently.  For comparison with

point-particle results, I don't think it makes much difference; the results

are gauge dependent anyway so differences on the order of the horizon size

cannot be interpreted physically.  Since the parameter file already has

horizon-finding built in, it is easier for you to use that.

If you want to figure out how to add the puncture tracker to the simulation,

you can start with these parameters:

ActiveThorns = "PunctureTracker"

PunctureTracker::track                      [0] = yes

PunctureTracker::initial_x                  [0] = $xp

PunctureTracker::which_surface_to_store_info[0] = 0

PunctureTracker::track                      [1] = yes

PunctureTracker::initial_x                  [1] = $xm

PunctureTracker::which_surface_to_store_info[1] = 1

IOASCII::out0D_vars = "PunctureTracker::pt_loc"

Replace $xp and $xm with the initial x coordinates of the +x and -x

punctures (this will be \pm TwoPunctures::par_b).  You then need to choose

two spherical surfaces

(https://docs.einsteintoolkit.org/et-docs/Einstein_Toolkit_standards) which

are not being used currently to store the puncture locations in.  If there

is already 0D output, just add the puncturetracker variable separated with a

space.

I

did some plots, what are really the combinations xx, xy, xz, yy, zz ?

Are they related to the trajectories of one BH (projections)? What

about the second BH?

You should have BH_diagnostics.ah1.gp and BH_diagnostics.ah2.gp.  These

correspond to the first and second BHs.  If you look at the top of these

files, you will see an explanation of the columns.  More information about

each column is available in the AHFinderDirect documentation

(http://einsteintoolkit.org/documentation/ThornGuide/ThornGuidech128.html#x144-2264000O4).

 Specifically, information about the BH_diagnostics output files is

at http://einsteintoolkit.org/documentation/ThornGuide/ThornGuidech128.html#x144-2274000O4.5.5

To plot the trajectory of one of the BHs, you want to plot column 3 and

column 4 in a parametric plot.

Cheers,

Jose

On Mon, Jan 16, 2012 at 4:39 AM, Ian Hinder <ian.hinder@aei.mpg.de> wrote:

On 14 Jan 2012, at 00:41, Jose Fiestas Iquira wrote:

Hi Ian,

I did the changes but it started and finished early. I am attaching

the qc0-mclachlan.err file. At the end there is a warning in one of

the Carpet files (mask_test.c)

The warning you see,

WARNING level 1 in thorn CarpetReduce processor 0 host qb517

  (line 120 of

/home/ettest24/Cactus/arrangements/Carpet/CarpetReduce/src/mask_test.c):

  -> Simulation domain volume and reduction weight sum differ

is a known issue (https://trac.einsteintoolkit.org/ticket/434) which was

fixed after the last release and the fix is only available in the

development version.  I believe that the warning is not fatal, and it should

not have terminated the simulation.  Can you also post the qc0-mclachlan.out

file?

Where can I find the puncture tracker?

The PunctureTracker thorn is part of the Einstein Toolkit thornlist, so you

should have it already.  However, I think the best thing for you to do

initially would be to look at the BH_diagnostics files for the apparent

horizon centroid locations for tracking the locations of the BHs.

Thanks,

Jose

On Fri, Jan 13, 2012 at 4:38 AM, Ian Hinder <ian.hinder@aei.mpg.de> wrote:

On 13 Jan 2012, at 12:32, Jose Fiestas Iquira wrote:

Yes, trajectories and wave forms would be enough for now. Which are

the names of this files? Many of the .asc files have data like kxx,

kxy, kxz, etc. Is there any description of them?

Not that I am aware of.  Files with extension .x.asc are 1D ascii output of

grid functions from CarpetIOASCII.  kxy is the variable name for the x,y

component of the extrinsic curvature tensor K.  The waveform file should be

in mp_psi4_l2_m2_r*.asc where * corresponds to the radius of the extraction

sphere.  However, looking at the qc0-mclachlan.par file, I see that there is

no wave extraction switched on.  You should be able to enable wave

extraction by adding something like the following to the parameter file:

ActiveThorns = "WeylScal4 CarpetInterp AEILocalInterp Multipole"

Multipole::nradii    = 3

Multipole::radius[0] = 30

Multipole::radius[1] = 40

Multipole::radius[2] = 50

Multipole::variables = "WeylScal4::Psi4r{sw=-2 cmplx=’WeylScal4::Psi4i’}"

Multipole::l_max     = 4

WeylScal4::fdOrder   = 4

(I haven't tested this, so let me know if it doesn't work)

I've just found that the usual PunctureTracker thorn is not enabled in this

example parameter file.  So to look at trajectories you will have to use the

apparent horizon centroids.  These are in the files BH_diagnostics.ah*.gp.

 The meanings of the columns are at the top of the files.  You want the

centroid x and y columns to plot in GnuPlot.

Thanks,

Jose

On Fri, Jan 13, 2012 at 12:41 AM, Ian Hinder <ian.hinder@aei.mpg.de> wrote:

On 12 Jan 2012, at 23:46, Jose Fiestas Iquira wrote:

Dear all,

I run the tutorial and found other interesting examples like the

McLachlan tool for Binary Black Holes.

Regarding the McLachlan tool,

Could somebody help me finding a description of the output? Is all

contained in the .asc files? I would like to visualize it.

Hi Jose,

What sort of output do you want to visualise?  Cactus thorns typically

output "lightweight" information such as BH trajectories and waveforms as

ASCII, and more heavyweight data -- like gridfunctions -- as HDF5.  For the

trajectories (from thorn Puncture Tracker) and waveforms (from Multipole)

you can use gnuplot or anything that can read standard ASCII output to

visualise them.  For gridfunctions in HDF5 format, I think the easiest way

to get started is to use VisIt, for which there is a Carpet plugin (though

installing VisIt is sometimes not so easy!).

Does anyone know if the Carpet plugin is distributed with VisIt yet?  I

believe that was the intention.

Cheers,

Jose

On Wed, Jan 11, 2012 at 7:06 PM, Jose Fiestas Iquira <jafiestas@lbl.gov>

wrote:

Thanks to Erik for advise. ETK example simulation run successfully.

On Wed, Jan 11, 2012 at 11:49 AM, Jose Fiestas Iquira <jafiestas@lbl.gov>

wrote:

Right, it looks good now:

./simfactory/bin/sim list-simulations

  static_tov              [ACTIVE (RUNNING), restart 0000, job id 595490]

Let see how it looks when it finishes. The example was set to 8 hours.

Thanks,

Jose

On Wed, Jan 11, 2012 at 11:45 AM, Erik Schnetter <schnetter@cct.lsu.edu>

wrote:

On Wed, Jan 11, 2012 at 2:42 PM, Jose Fiestas Iquira <jafiestas@lbl.gov>

wrote:

The only thing is that now

$ ./simfactory/bin/sim list-simulations

returns

Error: unknown command list-simulation

Aborting Simfactory.

Did you really type "list-simulations", and the error message says

"list-simulation" (without the final "s")?

-erik

--

Erik Schnetter <schnetter@cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/

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