[FMDenaro]

Originally Posted by LThomes

Yep, that's exactly what I was wondering... My solution tells that the mean velocity does not have a periodic pattern. What would you say about it? Probably a simulation error or is it possible?

The key is in understanding what is the "mean" field in URANS. In my opinion, this is not clear theoretically for such a problem. In principle, URANS has a more clear framework when the unstedy component in the mean field is due to an external force. A typical well suited case is the in-cylinder flow with a moving piston. Using URANS in a vortex shedding flow problem has some lack, at least in my opinion. If you would consider that, instead of an esemble averaging, the time-averaging is used, it would be more similar to a time-filtering in LES. In this case the range of resolved frequencies can give reason of a non exactly periodic solution.
I cannot say more, I never explored URANS for such problems...