You can visualize the results of the coupled simulation using e.g. ParaView. OpenFOAM uses the specific format `fluid-openfoam.foam`, which you directly load in Paraview or convert to VTK with `foamToVTK`. deal.II writes VTK files. Both Nutils solvers currently don not write VTK files (but their own in-situ visualization), but this can be added easily similarly to the [perpendicular flap solvers](https://github.com/precice/tutorials/blob/98a78fe2dc2f6c5d84b2b30d35d00352782236f8/perpendicular-flap/fluid-nutils/fluid.py#L227).

If you want to visualize both domains with ParaView, keep in mind that the different solvers may write results with different output frequencies.

There is an [known issue](https://github.com/precice/openfoam-adapter/issues/26) that leads to additional "empty" result directories when running with some OpenFOAM versions, leading to inconveniences during post-processing. At the end of `run.sh`, we call `openfoam_remove_empty_dirs` (provided by `tools/openfoam-remove-empty-dirs`) to delete the additional files before importing the results in ParaView.

Moreover, as we defined a watchpoint at the flap tip (see `precice-config.xml`), we can plot it with gnuplot using the script `plot-displacement.sh`. You need to specify the directory of the selected solid participant as a command line argument, so that the script can pick-up the desired watchpoint file, e.g. `plot-displacement.sh solid-dealii`. The resulting graph shows the vertical (y) displacement of the tip of the flap.