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-   -   [GAMBIT] mesh pipe in pipe (http://www.cfd-online.com/Forums/ansys-meshing/94976-mesh-pipe-pipe.html)

kolobei December 1, 2011 11:46

mesh pipe in pipe
 
1 Attachment(s)
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?

-mAx- December 2, 2011 01:45

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

kolobei December 2, 2011 04:07

thanks for the reply.Although i wonder something, maybe i have to unite the pipes?can i do that?

-mAx- December 2, 2011 05:21

yes you can.
If your pipes are still real volume, then go and unite them (boolean tool)

kolobei December 2, 2011 06:12

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.

-mAx- December 2, 2011 07:43

you can unite and then split your model where you want.
do you have a picture of an intersection between 2 pipes?

kolobei December 2, 2011 11:36

1 Attachment(s)
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?

kolobei December 3, 2011 06:57

well i tried to unite and then split volumes but iha ve a problem in splitig volumes.

-mAx- December 5, 2011 00:50

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.

kolobei December 5, 2011 08:24

what settings should i put in mesh to be more dense?

-mAx- December 5, 2011 08:28

reduce element size in the volume mesh panel

kolobei December 5, 2011 08:52

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.

-mAx- December 5, 2011 09:31

delete volume mesh (enable unused lower mesh)

kolobei December 5, 2011 09:40

well i go in "mesh>face>delete" and it deletes the round mesh, not the circle in the side

-mAx- December 5, 2011 09:41

mesh>volume>delete

kolobei December 5, 2011 09:47

it doesnt do that i want

-mAx- December 5, 2011 09:55

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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