Ah - multi-region meshes are a bit trickier, but I have done it a few times. The approach that worked for me was (after converting mesh to foam with

fluent3DMeshToFoam

). 1.

mergeBaffles -overwrite

to remove patches beteween my regions/cell-zones 2. remove leftover patch definitions with 0 faces, either manually or by running

createPatch -overwrite

with an empty createPatch dict. 3. Create mesh regions with

splitMeshRegions -cellZones -overwrite

This was using openFoam 11, so i dont know if it works using ".com/ESI" version. As I remember it was also a bit tricky to get the cell zones and interfaces right in the fluent mesher