Subashni Ravichandran
Ansys Employee

Hello Fuyu-m

I had a few discussion with my team and I also run a few tests and the conclusions are as below:

  1.  Discovery Live applies Rotating wall Boundary condition on only axially symmetric faces. 
    In the model shared by you, the Rotating wall BC has been applied to a half-cylinder face.
    Thereby resulting in inaccurate results.
  2. Performing a similar analysis using an axially symmetric face gave me consistent results.
    The results did not fluctuate in any unexpected way with varying fidelity.
    Higher fidelity produced a more accurate result.
    The Flow rate at Inlet and Outlet were consistent at different fidelity.