@ufechner7 I don’t know if this question is still relevant, but as @ranocha pointed out, we do have initial support for multi-physics simulations in Trixi.jl using volume coupling (sometimes called bulk coupling), e.g., for flow-gravity or flow-aeroacoustics problems. There is also a PR for coupling two or more meshes using surface coupling (aka interface coupling), but it has not yet been merged.
Activities regarding multi-physics simulations in Trixi.jl are to increase soon, since we have secured a research grant on bulk and interface coupling with Trixi.jl. The first PhD students and postdocs are starting in October and November, so we expect to start seeing feature updates in the next couple of months. Feel free to reach out to me personally if you have a specific question and whether it is (currently) viable to do in Trixi.