[Jinn]

Hi,

I was trying to implement the Spalart-Allmaras turbulence model into my FVM rotor solver, which can work well with the Baldwin-Lomax model.

The version of the S-A model I used is the "Standard" model on https://turbmodels.larc.nasa.gov/spalart.html#sa. I used the LUSGS scheme for time marching, and convective and viscous fluxes in the S-A model are 1st upwind and 2nd central scheme, respectively. The freestream nut is set to 3*nu as recommended. The case I am running is a hovering state of a 2-bladed rotor.

Now the computation suddenly diverges after 5 revolutions, when the force coefficients seem to have achieved a periodic solution. It is weird to me. Lowering the CFL number helps to delay the divergence but it still crashes finally.

Has anyone encountered similar problems? What are the possible causes of such a sudden divergence? Any ideas are welcomed!

Thanks in advance!!!