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-   -   How to specify an inlet boundary conditions for a fully developed gas flow in a duct. (http://www.cfd-online.com/Forums/fluent/75976-how-specify-inlet-boundary-conditions-fully-developed-gas-flow-duct.html)

legendyxg May 11, 2010 04:08

How to specify an inlet boundary conditions for a fully developed gas flow in a duct.
 
Dear everyone,

My model contains a rectangular duct with various kinds of gases flow through it. What I care is only the fully-developed region while I only know the mass flow rate. I found that if I specify the inlet boundary as a mass-flow-inlet type, the inlet region is not fully developed. So what kind of boundary type should I use in order to avoid the inlet developing length?

Thank you.

leonardo.morita May 11, 2010 05:30

Hello,
If you want a fully developed flow at inlet, you should firstly run another simulation, in which you impose periodic conditions or you have a sufficiently long developing region. Once you obtain a developed flow at the outlet of this system, you can write a profile (Write > Profile) for your velocity and then read it in your final case (Read > Profile). When setting boundary conditions, you'll see that this profile will be available ("constant" tab). See FLUENT User's Guide chapter 4.6 for some more details.

legendyxg May 11, 2010 07:32

I'll have a try and thanks for your help.


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