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[GAMBIT] mesh pipe in pipe

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Old   December 1, 2011, 12:46
Default mesh pipe in pipe
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george kolovadis
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hello my teacher gave me a project to work it.im new in gambit 2.2.30, i designed it but i want to run it into openfoam but the "water" does not go into all the pipes. As you can see in the picture i have set the walls, the inflow and the outflow.why doest it run correctly?
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Old   December 2, 2011, 02:45
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That means one (or more) pipe is not properly connected to other pipes.
For your information, you don't need to define the walls (except if you want to compute any force on special surface). Gambit will automatically sets all surfaces (without BC) as wall. Connected surfaces between volumes (>> split) are treated as interior.
Now for your problem: delete the walls-BC you defined, and re-export your mesh (with only inflow and outflow BC)
In openfoam, import your mesh and write the result for t=0. In paraview (or parafoam), display the wall surfaces, and check where is the surface which is an obstacle for your flowfield.
Alternatively you can lets your own wall-BC (renamed it with something different as "wall" since "wall" is used from Gambit). Export from Gambit, Import in Openfoam, and check if Openfoam exports a folder called "wall".
If yes, then diplay the surfaces and you will see where your problem is.
If you don't have "wall" entity, then your mesh should be ok
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Old   December 2, 2011, 05:07
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thanks for the reply.Although i wonder something, maybe i have to unite the pipes?can i do that?
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Old   December 2, 2011, 06:21
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yes you can.
If your pipes are still real volume, then go and unite them (boolean tool)
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Old   December 2, 2011, 07:12
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well i tried that, but i dont want to have a unite model.isnt there anything else i can do , so that the fluid can pass from all the pipes? although thank you for your answers, i really appreciate for your help.
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Old   December 2, 2011, 08:43
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you can unite and then split your model where you want.
do you have a picture of an intersection between 2 pipes?
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Old   December 2, 2011, 12:36
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yes thats the picture, but as you can see the small pipes are getting in the big one, i'll do it as you say as a second model and try it, but for the current is there a way to fix it and stay as it is?
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Old   December 3, 2011, 07:57
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well i tried to unite and then split volumes but iha ve a problem in splitig volumes.
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Old   December 5, 2011, 01:50
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Try to run first your model with united volumes (then when you get some results, try to enhance your mesh with splits, etc...)
BUT as I see your last pictures, you have to insert more cells in your pipes (I see only one cell in the smaller pipe). You need at least, 8-10 cells.
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Old   December 5, 2011, 09:24
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what settings should i put in mesh to be more dense?
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Old   December 5, 2011, 09:28
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reduce element size in the volume mesh panel
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Old   December 5, 2011, 09:52
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that worked great.i have a question although , how can i remove the mesh from the circles of the cylinders?i ask this because maybe there 'll be a problem in openfoam.
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Old   December 5, 2011, 10:31
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delete volume mesh (enable unused lower mesh)
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Old   December 5, 2011, 10:40
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well i go in "mesh>face>delete" and it deletes the round mesh, not the circle in the side
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Old   December 5, 2011, 10:41
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mesh>volume>delete
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Old   December 5, 2011, 10:47
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it doesnt do that i want
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Old   December 5, 2011, 10:55
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check how many volumes do you have.
If you united all your volumes, then you are suppose to have just one.
In volume/delete, click on the black arrow and it will open a list with all available volumes.
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