no convergence at laval nozzle
 

hello everyone,

i have a little problem and the suggestions in other threads couldn't solve it.

I'm simulating a supersonic flow (mach 1.2) with a laval nozzle with a far field. The problem is that my residuals start to oscillate after about 400 iterations, not going to convergence and there is the problem.
The inlet pressure for the nozzle is 2.424 bar, turbulence is intensity and viscosity ratio. The inlet pressure for the far field is 101325 pa and the outlet pressure is 100000 pa.

I use SST k-omega solver. fluid is ideal gas. It's implicit, roe-FDS, second order upwind, dp and the courant number is 6.

I need the residuals to convergence and go under 10e-5. (guidelines here)
I would be thankful for any help because I'm out of ideas.