I'm not an expert (I'm just learning OpenFOAM), but have you tried to find an example that uses the k-omega model in the Tutorials? For example: (/usr/lib/openfoam/openfoam2106/tutorials/incompressible/pimpleFoam/RAS/rotatingFanInRoom/). That might give you an idea of things to tweak in order to get better results. 🙂 You can also browse around here: https://www.openfoam.com/documentation/guides/latest/doc/guide-turbulence-ras-k-omega-sst.html