Hello, nI'm pretty sure that they would have diverged later because that's what always happens when I let it run. So I stopped the calculation to see in which direction the results are going. nThe mach number is around 0.2-0.25, the fluid is compressible air. When I solve with incompressible air it also diverges. nThe inlet area is 6*10^(-3) m^2, outlet area is 1.9*10^(-2) m^3. nActually the mass flow rate is 0.38 kg/s, I got that wrong in the question.