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Some initial difficulties

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Old   December 31, 2012, 06:52
Default Some initial difficulties
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Location: Milano, Italy
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Hi everybody!

I tried to find the answers to my problem in the forum, but without success
I'm a beginner with OF, and with SHM in particular, so I wanted to start with something simple: a pipe (because I need to learn about similar internal flows).

Now, I read the guide and I consulted the tutorials (the motorBike one in particular) but I have some problems.
For now, the most important is with the mesh. I created the surface, a pipe with a thickness, as .stl file. I used blockMesh to create the background mesh and then snappyHexMesh. The result is strange. Instead to obtain the pipe, I obtain something different: OF subtracts the surface I created from the background mesh... I don't understand why!

To be more clear, I attach the files "blockMesh" and "snappyHexMesh" and a figure.
If someone could help me, I'd be really grateful!

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File Type: jpg pipe1.jpg (44.7 KB, 28 views)
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File Type: zip (4.4 KB, 7 views)
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Old   December 31, 2012, 13:03
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Wouter van der Meer
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I am no expert, but I think your intial blockmesh should not go beyond the inlet/outlet of your pipe. if your blockmesh is to large SHM starts inside the pipe then follows the surface and comes to the outside of the pipe. Your surface is the only part that is not meshed.

hope this helps
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Old   February 4, 2013, 05:17
Default How could I add patches?
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After one month I'm here again.
Thanks Wouter for your answer, but i'm not sure was that my problem.

Now I have less problems (it seems) with the mesh, but I didn't solve all of them. I explain.
After blockMesh and SHM, OF creates just one patch for my pipe (the surface I exported), one for all of it. So I have a total of 5 patches: 4 for the faces of the background mesh and only one for the pipe. Instead, I'd like to have more of them for the pipe, like inlet, outlet, internal and external surfaces... But i don't know how to do!
Infact, I tried to launch a simulation, with simpleFoam: it works, but of course outside of the pipe, not inside! This because I can give it (in the simplest case) just a velocity, that is the same all around the pipe, on all my unique patch! It is of course unuseful!

Then, someone has an idea about what i could do?! I think, I need a way to add more patches, at least the one for the inlet! But how?!
Every kind of suggestion is well accepted, thank you!

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