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Uneven velocity profile as inlet

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Old   September 25, 2018, 02:57
Default Uneven velocity profile as inlet
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Elm
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Hi Foamers,


i do have an cylindric geometry with some inlet pipes at the bottom (see attachment).
Do you know if there is some inlet boundary conditions to model these pipes or an uneven velocity boundary?




I dont want to mesh all the small pipes, so please help me


(The picture of the pipes is just an example)


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Old   October 2, 2018, 15:59
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Hi Elm,


Have you considered created two different patches while meshing? You could then use two different fixed values in 0/.


Cheers,
Vincent
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Old   October 3, 2018, 02:49
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You may give the velocity at your patch as nonuniform List<vector> . If you don't made this before I recommend to start with uniform velocity and analyze one of the result files. All you gave compact will be nonuniform there and you may see which velocity belongs to which coordinate.
You have to give a 0 file in the same structure.
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Old   October 5, 2018, 05:18
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@hyFoam: Yes, the two patches way is my "dirty" solutions ;-)


@piu58 Thanks for that hint, that seems the perfect solution for me!
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Old   October 5, 2018, 08:34
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Hi,

both ways will work, but I would prefer the first one - building two patches based on the following reason:
  • If you have two patches, you will catch the circular behavior of the inlets
  • If you have one patch, you will probably get a uniform mesh at the inlet (depending on the meshing strategy), and therefore, you can apply the velocities only to flat, non-curved faces which might influence your result.

However, personally, two patches do not seem to be a 'dirt' workflow. The way, Piu is explaining would be excellent, if:
  • The flat/curvature inlets does not influence your solution
  • You have the center points of the inlet pipes; a small codedFixed boundary condition while reading a file that contains the center while calculating the area of the circles and evaluate the included face centers while applying the velocity field, is beautiful, simple and modifiable
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Old   October 8, 2018, 03:18
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Thanks for you detailed answer Tobi!
I misunderstood the solution of hyFoam, i'll try both ideas
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