[FFD]

Hello,
I have some issues choosing the right boundaries (I think its my issue).
To my setup:
I do have a non-newtonian fluid moving through a helix with changing diameter (2-7cm) and the K-Omega SST turbulence model.
The inlet pressure is 1bar. The pressure at the outlet is 45bar.

So as Inlet I choose the following parameters:
Total Gauge pressure: 100000
Supersonic/ Initial Gauge Pressure: 100000
Tke: 0.00175
Sdr: 54.668
Temp: 300K

Outlet:
Gauge Pressure: 4500000
Tke: 0.0001355
Sdr: 4.337
Temp: 510K

(Tke and Sdr are calculated with 0.1m/s (inlet) and 0.05m/s (outlet))
I also have a rotating wall with 100 rpm and 500K temp

My simulation is diverging everytime. I always get the message that the AMG-Solver diverged. Sometimesafter 3 iterations. Sometimes after 20 iterations. and sometimes even at the first iteration.

My Material is defined like this:
Density, Cp, Thermal Conductivity are constant and the viscosity is a function of shear stress and Temperature.
I also correct the dissipation enegery with a user defined function.
The user definded function was given to me and I think the math in it is correct.

Due to the kinematic viscosity of the material it is expremly prone to small changes. When I change the estimated Velocity from 0.1m/s to 0.15m/s my Sdr changes from 53 to about 250, so I need to make a good estimation here.

So I have the following questions:
How do I make a good estimation of my Boundaries?
What is the Total Gauge Pressure and what is the Supersonic Gauge Pressure? (I just used both as the same value. But it might be wrong).
How do I choose my Tke and Sdr correct, when I do not know some parameters like the reference velocity ( 0.01m/s is just an estimation)? How should I choose my parameters in this situation?

Thanks for the help in advise and Best regards,

FFD

[AlexanderZ]

Put
Supersonic/ Initial Gauge Pressure: 0
So you will get 1bar pressure at inlet

Best regards