First of all, some context regarding our tutorials: We try to keep them simple and small, so that they can run quickly on a laptop. This is why most of the cases you find there are in 2D. However, we typically try to support 3D in all adapters.
In this context, the heat exchanger tutorial was only meant to demonstrate a more realistic scenario. It is one of our first tutorials, and unfortunately we rely on an already generated mesh, so it is difficult to reproduce it with other solvers. That’s why you only see the OpenFOAM-CalculiX-OpenFOAM variant there.
Regarding FEniCS, maybe @IshaanDesai could answer in more detail, but I see that the PRs mentioned in the post you referred to have been merged. In any case, FEniCS is supposed to be a framework in which you can code your own model, so expect a bit more work (but also more control).
In principle, every adapter should mention such information in its own documentation section in this part of the documentation: Overview of adapters | preCICE - The Coupling Library If some adapter page is missing such information, please open an issue in the respective repository, or directly edit the page (click “edit” on the website and submit a pull request) and we will pick it up from there.
Finally, we are starting to work on standardizing the adapters, so that you can make assumptions for all adapters, without having to look into some features page.
Thanks @Makis for the answer and the additional context. In the case of FEniCS, I was also referring to this recent list of limitations. These are not documented in the preCICE docs from what I can see.
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.