Water Hammer Tutorial

[franiqui]

This PR adds a new Partitioned Water Hammer tutorial demonstrating transient 1D–3D coupling with preCICE for compressible pipe flow.

The tutorial is particularly relevant as it provides a transient benchmark for testing the axial geometric multiscale mapping under wave-propagation conditions. Unlike steady pipe examples, this case introduces pressure waves traveling across the coupling interface, making it a meaningful validation scenario for mixed-dimensional coupling.

It includes 1D–3D and 3D-1D, as well as 1D–1D and 3D–3D configurations for comparison and validation.

Checklist:

• I added a summary of any user-facing changes (compared to the last release) in the changelog-entries/<PRnumber>.md.

[MakisH]

Thank you for the clean PR! See some first comments on the structure.

I have not yet looked into the codes or the parameters, I would do that once the locations of the files have converged, to not lose track of the suggestions and changes.

The 3D and 3D-3D cases run, anything with the 1D code does not at the moment, but this is probably related to my system (see also #648 (comment)).

Please add some content to the PR description as well.

[MakisH]

Update: I resolved a few conversations that have already been addressed. What is still open is still relevant.

This looks already very close to merging. Together, let's polish the README.md and add the 1D-1D and 3D-3D as options, since this is very low effort and high benefit.

[MakisH]

I tried all combinations, they all start and the plotting script works for all.

Some small changes in the plotting script would make this easier to use.

[MakisH]

If I now run only the 1D-3D, I get:

$ python plot-pressure.py 
[INFO] Case '3D-1D' skipped: file not found (fluid1d-right-nutils/probes.txt)
[INFO] Case '1D-1D' skipped: file not found (fluid1d-right-nutils/probes.txt)

and two identical pictures for the 1D-3D and the 3D-3D, while the latter should not be there: