AVL Fire transonic simulation
I'm doing a simulation of transonic flow through a nozzle. I would like to know the typical setting needed in AVL FIRE v8.2 for such a simulation. I have convergence for a combination of mass flow and pressure boundaries, but find it hard to achieve convergence for total/stagnation pressure as inlet and static pressure as outlet boundaries. I can only achieve convergence for very small inlet and outlet pressure differences, i.e. only for subsonic flow.
What would be the first thing I should do?
I have activated all the equations: momentum & energy. However I am unsure about compressibility options in AVL Fire. At the moment I am using compressible. Which between compressible and supersonic is the better choice?
What order of under-relaxation factors are typical to achieve convergence for transonic flow?
BTW, the nozzle I'm simulating is very small, about 3mm in diameter.
Is there a recommended differencing scheme & linear solver for transonic flows/this type of problem? I seem to remember MARS to work for some transonic simulations in Star-CD (is this correct?), does anyone know which of the schemes offered in AVL is similar to MARS?
Finally, is it possible for Fire to have a boundary surface which is sonic/supersonic? I know this is not good practise for Star-CD.
I'm new to CFD, so any insight(s) however small may be of help.
i'm doing some simulations in the same field as you do so if you are interested to share ideas over this send me an email on firstname.lastname@example.org
thanks a lot
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