Follow the instructions here

May 23, 2025 · View on GitHub

Cactus Code Thorn ICPertFLRW_GRH Author(s) : Robyn L. Munoz Maintainer(s): Robyn L. Munoz Licence : GNU General Public License

Purpose of this Thorn

This thorn provides initial conditions for an FLRW metric perturbed with the comoving curvature perturbation Rc in the comoving gauge. Rc is defined as a sum of sinusoidals, cosines or exponentials whose parameters are defined in param.ccl.

While the metric only have first order scalar perturbations, the extrinsic curvature and energy density are computed exactly in full from the Hamiltonian constraint, hence vector and tensor perturbations are initially present at higher order. Metric quantities are provided to ADMBase while fluid quantities are passed to HydroBase.

Copyright

This thorn is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This thorn is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this thorn. If not, see http://www.gnu.org/licenses/.

You may contact the author at : r.l.munoz@sussex.ac.uk

Publications

Article where these initial conditions are described: @article{M.Bruni_etal_2014_Mar, title = {Non-Gaussian initial conditions in $\Lambda$ CDM: Newtonian, relativistic, and primordial contributions}, author = {Bruni, M. and Hidalgo, J. C. and Meures, N. and Wands, D.}, journal = {The Astrophysical Journal}, volume = {785}, number = {1}, pages = {2}, year = {2014}, month = {3}, doi = {10.1088/0004-637X/785/1/2}, archivePrefix = {arXiv}, eprint = {astro-ph/1307.1478}}

Article where these initial conditions are further decribed and ICPertFLRW_GRH is developped and tested: @article{R.L.Munoz_M.Bruni_2023, title = {Structure formation and quasispherical collapse from initial curvature perturbations with numerical relativity simulations}, author = {Munoz, R. L. and Bruni, M.}, journal = {Physical Review D}, volume = {107}, number = {12}, pages = {123536}, numpages = {26}, year = {2023}, month = {6}, doi = {10.1103/PhysRevD.107.123536}, archivePrefix = {arXiv}, eprint = {astro-ph/2302.09033}}

How to implement this thorn into Einstein Toolkit:

===== 1) Have a working version of Einstein Toolkit

Follow the instructions here

https://github.com/nds-org/jupyter-et/blob/master/tutorial-server/notebooks/CactusTutorial.ipynb

Don't forget to try to run HelloWorld

#If you're doing this on an HPC

cd pathtocactus ./simfactory/bin/sim setup-silent --machine=HPCname ./simfactory/bin/sim build --machine=HPCname --thornlist=thornlists/einsteintoolkit.th

#The paths of the HPC config files are:

pathtocactus/simfactory/mdb/machines/HPCname.ini

pathtocactus/simfactory/mdb/optionlists/HPCname.cfg

pathtocactus/simfactory/mdb/runscripts/HPCname.run

pathtocactus/simfactory/mdb/submitscripts/HPCname.sub

===== 2) Modify Time

In arrangements/CactusBase/Time/param.ccl change

private: CCTK_KEYWORD dtfac "The standard timestep condition dt = dtfac*max(delta_space)"

to:

restricted: CCTK_KEYWORD dtfac "The standard timestep condition dt = dtfac*max(delta_space)"

This is because dtfac is overwritten

Time::dtfac = ICPertFLRW_GRH_time_fac * scale_factor

===== 3) Modify GRHydro remove mask

In arrangements/EinsteinEvolve/GRHydro/src/GRHydro_UpdateMask.F90

when you see

atmosphere_mask_real(i,j,k) = 1 atmosphere_mask(i,j,k) = 1

change the 1 to 0

This is to not have the atmosphere interfere with underdense regions

===== 4) Include ICPertFLRW_GRH in Einstein Toolkit

link

cd path_to_Cactus/Cactus/arrangements/EinsteinInitialData/ ln -s path_to_thorn/ICPertFLRW_GRH .

add to Cactus/thornlists/einsteintoolkit.th, in EinsteinInitialData section

EinsteinInitialData/ICPertFLRW_GRH

===== 5) Compile Einstein Toolkit

in Cactus directory

./simfactory/bin/sim build -j2 --thornlist=thornlists/einsteintoolkit.th

Or

./simfactory/bin/sim build --machine=HPCname --thornlist=thornlists/einsteintoolkit.th

===== 6) Run test.par to check if it works

./simfactory/bin/sim create-submit test_ICPertFLRW_GRH --parfile=arrangements/EinsteinInitialData/ICPertFLRW_GRH/test_ICPertFLRW_GRH.par --procs=1 --num-threads=1

Or

./simfactory/bin/sim create-submit test_ICPertFLRW_GRH --machine=HPCname --parfile=arrangements/EinsteinInitialData/ICPertFLRW_GRH/test_ICPertFLRW_GRH.par --procs=1 --num-threads=1

===== 7) Check the output with

tail -30 ~/simulations/test_ICPertFLRW_GRH/output-0000/test_ICPertFLRW_GRH.out you should see:

Iteration Time | ADMBASE::gxx | ADMBASE::kxx | HYDROBASE::rho | ML_BSSN::H | minimum maximum | minimum maximum | minimum maximum | minimum maximum

    0     1.000 |    0.0000235    0.0000235 |   -0.0000156   -0.0000156 |    0.0530351    0.0530682 |   -0.0000001    0.0000001
    1     1.018 |    0.0000240    0.0000240 |   -0.0000157   -0.0000157 |    0.0511504    0.0511828 |   -0.0000001    0.0000001
    2     1.037 |    0.0000246    0.0000246 |   -0.0000158   -0.0000158 |    0.0493645    0.0493961 |   -0.0000001    0.0000001
    3     1.055 |    0.0000252    0.0000252 |   -0.0000159   -0.0000159 |    0.0476704    0.0477013 |   -0.0000001    0.0000001
    4     1.073 |    0.0000258    0.0000258 |   -0.0000160   -0.0000160 |    0.0460621    0.0460923 |   -0.0000001    0.0000001
    5     1.091 |    0.0000263    0.0000264 |   -0.0000161   -0.0000161 |    0.0445339    0.0445634 |   -0.0000001    0.0000001
    6     1.110 |    0.0000269    0.0000270 |   -0.0000162   -0.0000162 |    0.0430804    0.0431093 |   -0.0000001    0.0000001
    7     1.128 |    0.0000275    0.0000276 |   -0.0000163   -0.0000163 |    0.0416970    0.0417252 |   -0.0000001    0.0000001
    8     1.146 |    0.0000281    0.0000281 |   -0.0000164   -0.0000164 |    0.0403791    0.0404067 |   -0.0000001    0.0000001
    9     1.164 |    0.0000287    0.0000287 |   -0.0000165   -0.0000164 |    0.0391227    0.0391498 |   -0.0000001    0.0000001
   10     1.183 |    0.0000293    0.0000293 |   -0.0000165   -0.0000165 |    0.0379241    0.0379506 |   -0.0000001    0.0000001
   11     1.201 |    0.0000299    0.0000300 |   -0.0000166   -0.0000166 |    0.0367797    0.0368057 |   -0.0000001    0.0000000

INFO (Carpet): Terminating due to cctk_final_time at t = 1.200794

===== 8) Be happy