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debris March 21, 2006 12:11

Hi, I'm trying to mesh a "d

I'm trying to mesh a "disc" with the "butterfly" method. I've done 4 patches for each quarter of the ciruclar geometry, and 8 patches for faces to merge (in blockMeshDict).

When I don't write anything in mergePatchPairs, I don't get any error message. But when I write patches to merge in mergePatchPairs (in blockMeshDict), I get this strange error message :

--> FOAM FATAL ERROR : Face 3735 reduced to less than 3 points. Topological/cutting error B.
Old face: 2(626 624) new face: 2(626 624)

From function void slidingInterface::coupleInterface(polyTopoChange& ref) const
in file slidingInterface/coupleSlidingInterface.C at line 1680.

FOAM aborting

I don't know why I get this message because my mesh seems to be correct. When I run it into paraview, I don't see any block problems, and faces to merge are exactly at the same place.

I'm pretty trapped with this problem, I hope you could help me. Thanks for your answers ^^.

hemph March 22, 2006 11:32

Hi Julien, I meshed (the ins
Hi Julien,
I meshed (the inside of) a pipe not to long ago. If you want, I can send you the file I used. No sliding interfaces or merging of patch pairs in my case though!

debris March 22, 2006 12:47

Hi Rasmus, Did you use a "b
Hi Rasmus,

Did you use a "butterfly" method to mesh your pipe or did you simply mesh it with arc or spline edges ?

Even if you didn't have mesh your pipe with a "butterfly" method, the file you used could perhaps help me. It would be cool if you can send it to me ^^. I'm new on this forum, but I think you can send me the file on my email adress in my profile.



hemph March 23, 2006 04:29

Here is a picture of the mesh.
Here is a picture of the mesh. The script I used to generate it is attached. It was done using the preprocessor m4 (search the wiki for more info). You change the radius, length and wanted number of cells in pipeMesh.m4 and generate your blockMeshDict as:
m4 pipeMesh.m4 > blockMeshDict
Then you run blockMesh on the file as usual. Hope it helps! pipemesh.m4

debris March 23, 2006 10:51

I've tried your mesh and it wo
I've tried your mesh and it works correctly (nice little script btw). You've done your mesh with arc edges, but I can't do my mesh with the same method, because my blockMeshDict file is written from a points file realized by another mesh soft. I have to merge some of the patchs

Here is a picture of my mesh, my mesh sounds good but merging patches doesn't work and I get boundary inside my pipe...

My blockMeshDict is attached.

Thanks for your help. I'll maybe try to mesh my points file with another method (like yours) if I can't figure out how to merge theses 8 patches.


debris March 23, 2006 11:05

Sorry, I forgot the blocMeshDi
Sorry, I forgot the blocMeshDict file...

debris March 23, 2006 11:18

The second part of the blockMe
The second part of the blockMeshDict. I'm not really used to use this kind of forum ;-). (I can't edit my posts, sorry for triple post).

debris April 3, 2006 10:57

Ok, I've fixed my problem. I'v
Ok, I've fixed my problem. I've created a double line where I needed to merge some patches in order to merge my patches from a external patch to another one.

Thanks for your help Rasmus btw.

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