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asamit September 2, 2011 18:18

How to create cyclic boundary(fan B.C.) in openFOAM200.
Are there any procedure I can try?

asamit September 3, 2011 06:14

1 Attachment(s)
I would like to create cells like fig.b shown in the attachment. But, I get the cells like c.

asamit September 4, 2011 06:45

How can I create cell shown in figure b, using snappyHexMesh and stl file?

asamit September 5, 2011 07:13

Are there any ideas to merge faces red and blue shown as figure c? I want to get inner faces shown as figure b?

wyldckat September 5, 2011 14:33

Greetings asamit,

AFAIK interior patches cannot be created inside a mesh in OpenFOAM. Mmm, I guess I'll quote (source):

Originally Posted by
Fluent allows the user to define a patch which is internal to the mesh, i.e. consists of the faces with cells on both sides. Such patches are not allowed in OpenFOAM and the converter will attempt to filter them out.

If you want to force the flow of a fluid, then you'll have to use something else, like setFields (see Breaking of a dam) or swak4foam.
You can select the cells that next to the desired STL surface and then use that cellSet as a reference in either setFields or swak4foam. I can't remember properly, but I think that setSet is what you'll need.

Another possibility would be to use one of the chtMultiRegion*Foam solvers, but this requires that you have two mesh volumes, not just one; i.e., you would have to split your mesh into two regions. See the tutorials at "tutorials/heatTransfer" for more ideas.

Best regards and good luck!

asamit September 7, 2011 08:48

Hi, Bruno
Thank you for replying. I must examine swak4foam.

asamit September 8, 2011 07:35

If I could use boolean operation between normalToFace and patchToFace, within setSet command, I could get the blue line shown in figure b.

asamit September 9, 2011 23:46

This is wrong. constant/PolyMesh/faces already has red and blue faces, before applying patchToFace.

asamit September 10, 2011 10:53

1 Attachment(s)
I modified constant/polyMesh/boundary by hand.
type cyclic;
→ nFaces 52;
→ startFace 25148;
matchTolerance 0.0001;
neighbourPatch fan_half1;
type cyclic;
→ nFaces 52;
→ startFace 25200;
matchTolerance 0.0001;
neighbourPatch fan_half0;

I would like to do this by command.

asamit September 10, 2011 21:57

1 Attachment(s)
How can I reduce zigzag?

asamit September 12, 2011 03:01

I give up on this. Next, I will try fieldSet and chtMultiRegion. Are they possible to simulate a P-Q? Any ideas?

wyldckat September 20, 2011 16:14

Hi asamit,

I don't know if you figured out the solution to your problem, but here is a couple of old threads that I've reviewed just now: - there you will have access to more information about a case that uses cyclic patches that are next to each other, which sounds a bit like what you are looking for.

As for modifying from the command line something in a dictionary/boundary file, look at the examples for using changeDictionary, by running this command:

find $WM_PROJECT_DIR -name changeDictionaryDict
Best regards and good luck!

asamit September 23, 2011 09:11

Hi Bruno,

I gave up on checking chtMultiRegion or changeDictionary. I found fanPressure BC. It works fine. It does not require creating identical mesh that required for a Type cyclic.
Thank you for many advices.asamit

mirko September 23, 2011 09:51

What about using baffles? (I have never used them myself). But from the tutirials, they seem to be designed to provide zero-thickness flat bodies inside the computational domain.


asamit September 24, 2011 20:42

I have tried faceSet, cellSet, faceZoneSet, and createBaffles. But they did not work well with snappyHexMesh.


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