The build and running of ExaGRyPE is wrapped by a Python API for convenience.

By calling the Python script in a command terminal, one can easily generate an executable that can run on any computational platform, from a student's laptop to supercomputer clusters. Different scenarios can be picked by feeding different physics parameters into the Python script; the simulation setup and running parameters can also be controlled directly via the command line.

Users are referred to the general Tutorials of ExaHyPE 2 if they are interested in what is going on behind the screens.

Run the benchmark

Two black holes rotate around each other in a quasi-circular orbit, and finally merge at the center in this scenario. We set the initial physics conditions of the system following this paper, Table I. Again, the following example is not suitable for a normal PC:

python3 ccz4.py -impl fd4-rk1-dsl -s two-punctures -maxh 0.4 -minh 0.04 -ps 8 -plt 0.5 -et 120 -exn bbh --domain_r 12.0 --ReSwi 6 -cfl 0.1 -outdir /path/to/data/folder/ --KOSigma 8.0 --BBHType 2 -sommerfeld -so -ext adm -interp second_order -restrict second_order

ccz4

Definition ccz4.py:1

This example should yield two black holes rotating and finally merging at the center.

Typing parameter –help makes the Python script yield further information and an explanation of each parameter option. We recommend users not to change the running parameters of ExaGRyPE during benchmarking, as the parameter space is vast and some combinations lead to unpredictable behaviour.

Clean up old and temporary files

The following statements remove all the glue code and auto-generated C++ files. This would be useful when you want to make sure no legacy code is around. There is no risk in deleting them - if you rerun the Python script, they will all be re-created.

rm *.o *.cmake
rm README-*.md
rm Makefile CMakeLists.txt
rm Abstract*
rm -rf celldata facedata globaldata observers tasks vertexdata repositories

To get rid of the output files, type

rm *patch-file *vtu *.pvd *.bak *.csv

Visualization

See Visualization of ExaGRyPE Output

Please notice the spatial filter is enabled by default, so the output of the examples above would be a slice of the x-y plane in the domain, instead of a complete cube.