Like mentioned in https://github.com/precice/fenics-adapter/issues/149 there are some restrictions for 3D cases with the FEniCS adapter. From the overall design perspective of the adapter 3D should not be a problem, but it has not been tested. Unfortunately, I currently don’t have the time to come up with a 3D tutorial on my own, even though I think this would be a reasonable next step to get some more security in this direction.
Also note that FEniCS is basically legacy, because FEniCS-X has been released. This also holds me back from “investing” a lot in the FEniCS adapter at the current point in time. For the FEniCS-X adapter the situation with 3D is similar: No tutorial and no tests at the moment but this is not a general problem with the design, but only with time and resources.
Like @Makis mentioned: For everything that seems to be missing in the documentation, every pull request is very helpful! Feel free to suggest some changes and I’m sure we will find a place to put the information.