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Old   May 31, 2007, 07:15
Default Pressure Outlet
  #1
Xiana
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Hi Fluent users,

I have a problem with the boundary condition Pressure Outlet for an incompresible fluid.Iīve defined it as 0 Gauge Pressure but I have some backflow and I donīt get the mass balance to converge. Iīve tried with the target-mass-flow-rate on and off, with both methods 1 and 2, and with a lower relaxation-factor but the mass balance still doesnīt agree. What should I do?

Thank you very much

Xiana
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Old   May 31, 2007, 08:34
Default Re: Pressure Outlet
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Prasad Dudhgaonkar
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Convergence also depends largely upon descritazation scheme and also on turbulence model and/or other models you're using. Can you please make your problem somewhat more clear in this regard?

Best wishes
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Old   May 31, 2007, 10:07
Default Re: Pressure Outlet
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Xiana
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Sure, I am simulating a rotating fluid between 2 coaxial cilinders and I use the Reynolds Stress Model for the turbulence. The discretization schema that I use is PRESTO! for the Pressure and First Order for the momentum.

kinds regard
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Old   June 5, 2007, 05:50
Default Re: Pressure Outlet
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Prasad Dudhgaonkar
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It sounds fine. RSM model needs a fine mesh.. almost double the number of cells than other two-eq turbulence models. Hope you made sure that your mesh is good in that aspect. You may even try RNG k-e.
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