Hi Konstantin,

To me, it looks like you would like to run the cosmo_box_gravity_only_3d example
However, judging from the output, in particular

Code was compiled with settings:


it looks like Arepo is not compiled with the correct Config.sh file.
In your case, e.g. the SELFGRAVITY flag is not active, which means that
Arepo will not perform a gravity calculation. Since the test-case also does not include any gas cells,
this means that there are essentially no forces calculated and therefore the simulation is very fast.

To compile Arepo with the correct Config.sh file, type

make CONFIG=./examples/cosmo_box_gravity_only_3d/Config.sh BUILD=./examples/cosmo_box_gravity_only_3d/build EXEC=./examples/cosmo_box_gravity_only_3d/Arepo

from the ./arepo directory.

Alternatively, you can just go into test.sh, comment out all test-cases but the one you like and remove the rm -rf ./run statatements.
Then execute via bash ./test.sh
This will copy the test-case over to a directory ./run/examples/…
compile it and run it.

Note that the time variable and therefore also the TimeMax parameter represents the so-called scalefactor for all cosmological simulations (https://en.wikipedia.org/wiki/Scale_factor_(cosmology)), therefore, I would leave it at 1 since this represents the age of the universe.