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Convergence issue in Fluent

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Old   April 20, 2011, 04:52
Default Convergence issue in Fluent
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Javier
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Hello.



I am having some problems finding convergence with my case of study. I am studying the flows in between the blades of a high speed centrifugal pump impeller.


I cannot make the residuals go any lower after 500 hundred iterations approx. It seems like they are stuck.


The order of my residuals are:
  • Energy ~10-5
  • X, Y, Z, Velocity ~10-4
  • Continuity, k and epsilon ~10-2

I monitor the mass flow rate at the outlet and it gets stable after 500 iterations so it seems like I reached convergence but my lab mates told me I need at least to reach 10-3

I’ve looked at the results and everything seems to be okay. Tip speed, Inlet/outlet velocity, static and total pressure, mass flow rate, velocity vectors…

Can I trust these results? Or how can I improve the residuals? I've done many different tries... It weirds me out that which such less iterations I could get some good results in something that theoretically seems complicated… I’ve done some other simpler studies with Fluent and it required me many more iterations.

Any suggestions?
Thanks
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