Sorry, I am using p_rgh, which is why I have it in my preciceDict. I am not directly using p.
Regarding the phase-related variables: this shouldn’t be an issue for interFoam based solvers though, right? They only solve for one velocity equation, right?
I tried running the case only with interFoam and the solvers do mostly what I expect, except for the fact that in the Fluid-2 domain at the outlet, the alpha values are a bit larger than 1. I assume the issues are somehow part of my setup then.
I assume that there are the values that preCICE gives, right? Not the values that Fluid1 originally computes.
@Fujikawas is currently working on an extension of the IQN to bound values, and this could be a nice use case of that feature.
Is there already a timeplan for the release?
There is no specific timeplan for this feature, but this is the respective PR for treating the overshooting issues: Add transformation in acceleration methods to treat bounded values by Fujikawas · Pull Request #1952 · precice/precice · GitHub
With nice use cases and feedback, any development can get faster! 
For you, right now, one alternative option would be using Aitken instead of IQN (with the usual performance disadvantages).
By the way:
Does this mean that you used the same setup, but a different solver? Do you think this is an issue with the solver, or that the adapter does not fully cover your solver?
Hi Makis, I tested the solver again the same case with coupling and without coupling and it seems like the solver does not do what I expected from the start. All coupled fields dont match with the non coupled case. Do you think this supports your idea that fields from a potential solver split do not get coupled properly? If it helps: I am using the openfoam-org-adapter with OpenFOAM-6
Hi @dennis,
sorry for delay, I overlooked your reply. Do you have any new information to add?
Partitioned flow simulations are definitely quite tricky, and I cannot give absolute answers on what works.