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-   -   help - Running Converging Diverging Nozzle with a shock wave (http://www.cfd-online.com/Forums/fluent/106602-help-running-converging-diverging-nozzle-shock-wave.html)

Daco September 3, 2012 08:23

help - Running Converging Diverging Nozzle with a shock wave
 
Hi!

I have recently started to work with fluent using the tutorial in the link:

https://confluence.cornell.edu/displ...ow+in+a+Nozzle

They solved the nozzle problem for the case the flow is supersonic in all the nozzle with no shocks. I have succeeded to recapture their results.

Next I tried (independently) to solve the same geometry with a higher outlet static pressure to get (theoretically) a shock wave in the diverging section of the nozzle.

The total pressure at the inlet is atmospheric (101325 Pascal).
I tried to input several outlet pressure: 20,000 Pa, 30,000 Pa and such
and after running the program the solution didn't converge and I didn't get any good results (the residuals went up instead of down)

My question is, What could be the cause for this divergence?

As I said, theoretically, A shock wave should occur.
Does it require any special attention? setup settings or meshing.. etc.

Could it be that the divergence occurs due to a too coarse mesh?
(I was told that the mesh in the tutorial is quite coarse)


Thanks ahead ,

Daniel


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