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Old   September 30, 2009, 16:30
Default boundary conditions
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I have a problem with bc 'pressure outlet'. When the flow reaches the edge of domain with this bc the process is not converged. What should be set for this bc?. Could you please helop me with this.

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Old   October 1, 2009, 13:10
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Tim Maguire
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I used to have that problem too.

You can either re-mesh at that outlet so it is more refined, or try and relax your tolerances.

I would try the tolerances first and then let it come to a converged solution.

Also, sometimes it just takes a while for the pressure outlet to have convergence at all the nodes.
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Old   October 1, 2009, 13:32
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Many thanks,
I will try to do both. As I understood the mesh should be more fine on the pressure outlet? In my case it is slightly coarser.
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Old   October 1, 2009, 16:30
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Check if you have reverse flow at the outlet. Add a length/domain at the outlet.
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Old   October 2, 2009, 08:49
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I set momentum boundary condition 'pressure gauge' to -10, and I had no back flow. I tried to extend domain but only effect I got it was extend of time of converged process. In some cases it helps and after some time process is converged again, but not every time.

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