TwoPunctures (GRChombo/GRTeclyn)

This repository originates from the standalone TwoPunctures code which in turn comes from the original Einstein Toolkit thorn TwoPunctures.

It has been modified to allow integration with GRChombo and GRTeclyn.

Physics

The code creates Bowen-York initial data for two puncture black holes using a single domain spectral method. The method is described in Marcus Ansorg, Bernd Brügmann, Wolfgang Tichy, "A single-domain spectral method for black hole puncture data" PRD 70, 064011 (2004) (arXiv:gr-qc/0404056).

GRChombo integration

To build the BinaryBH GRChombo example with TwoPunctures initial data, set the environment variable TWOPUNCTURES_SOURCE to the location of the Source subdirectory of this repository. Note that the parameters used are different to the vanilla BinaryBH example.

There is also a standalone example in this repository which can be used to check the bare and ADM masses of the final TwoPunctures result. To build this code, the GRCHOMBO_SOURCE environment variable must be set to the Source subdirectory of the GRChombo repository.

In either case linking with the GNU Scientific Library (GSL) is required.

GRTeclyn integration

To build the BinaryBH GRTeclyn example with TwoPunctures initial data, set the makefile variable USE_TWOPUNCTURES = TRUE. By default, the build system will assume this repository is cloned next to GRTeclyn i.e. /path/to/GRTeclyn/../TwoPunctures (like AMReX) but this can be overridden by setting the TWOPUNCTURES_HOME variable. Both of these variables can be set in the following ways:

• on the command line e.g.

  make -j 4 USE_TWOPUNCTURES=TRUE TWOPUNCTURES_HOME=/path/to/TwoPunctures
  

• in the Make.local-pre or Make.local files located in amrex/Tools/GNUMake
• by setting it as an environment variable

As for GRChombo, it requires linking with the GNU Scientific Library (GSL). If necessary, the GSL install location can be passed to the build system by setting GSL_HOME.

Note

TwoPunctures parameter names differ between GRChombo and GRTeclyn.

Note

When running GRTeclyn on GPUs, TwoPunctures will still run and interpolate the data onto the grid on the CPU. In this case, since you will generally have a much greater number of cells per MPI process, spectral interpolation will be very slow.

License

The authors of the original TwoPunctures code are Marcus Ansorg, Erik Schnetter, Frank Löffler. The modification to the standalone code on which this repo is based was done by Federico Guercilena, Sven Köppel

This code is licensed under the LGPLv2.1 license. Please see the LICENSE file for details.