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Old   December 19, 2002, 09:47
Default wall at the exit
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Olivier Macchion
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Hello people !

My geometry is a diffuser whose section is circular at the inlet and is rectangular at the exit. The angle of the diffuser is large so there is separation.

To model this and keep an Outlet boundary condition at the exit, I have extended the duct by 10 diameters at the exit. But it says that it must add a wall at the outlet to prevent flow to flow in through the outlet. So I added 3 diameters more at the outlet, and I got the same problem after 4 iterarions.

Is there someone who would have another suggestion to solve this problem ?

Thank you very much and happy Christmas everybody !

regards

Olivier
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Old   December 19, 2002, 11:23
Default Re: wall at the exit
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Holidays
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Use the option "opening" or continue as it is as this may be due to the initiation of the flow (you my consider an initial guess); there's a key word to get rid of th walls (it's in the manual) but I would still prefer to use the "opening" boundary...
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Old   December 19, 2002, 11:37
Default Re: wall at the exit
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Olivier
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Thank you !

Happy Christmas !

Olivier
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Old   December 19, 2002, 20:53
Default Re: wall at the exit
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Neale
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Olivier,

The walls are likely fine and this is probably just a "transient" effect, i.e. it will go away. Get a converged solution and see if they still exist. If so, then you might need to switch to an opening.

Neale

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Old   December 22, 2002, 15:41
Default Re: wall at the exit - Merry Christmas !
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Olivier
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Thank you Neale !

I launched a calculation and I will see if it converged as soon as I get back from holidays.

Have nice fests for the New Year !

Olivier
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