[BassBass]

Hello,
I am currently working on the simulation of a converging diverging over-expanded Nozzle for a pressure induced flow using rhoCentralFoam, the flow in the nozzle is steady and satisfies basic aerodynamics theory.
My problem is that the flow outside of the nozzle keeps being unsteady and far from the nozzle the flow detaches itself and oscillates as if there were some sort of instability which isn't what I would expect.

I've tried different boundary conditions for the outlet and my walls (waveTransmissive, zeroGradient, fixedValue) but none of them seem to make the flow become steady.

I've linked my case if anyone could to take a look and help me that would be great,
Thanks.