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Meshing with OpenFOAM: errore in checkMesh

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Old   May 6, 2016, 05:48
Default Meshing with OpenFOAM: errore in checkMesh
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Hello everybody.
I'm quite new in OpenFOAM since I have been using it for some months, and I registered a problem in using snappyHexMesh.
I am trying to mesh a domain around an airfoil in order to simulate compressible flows, but when I check mesh with checkMesh utility there's this errore message:

***Number of edges not aligned with or perpendicular to non-empty directions: 56148
<<Writing 83645 points on non-aligned edges to set nonAlignedEdges


At the following link you can find my case:
Mesh

Thank you in advance for everyone is going to reply and help me.
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Old   May 7, 2016, 14:33
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Hassan Kassem
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Hello,



This error mainly means that empty BC is used but the mesh isn’t 2D.
The problem is that you are trying to create 2D mesh using snappyHexMesh which is 3D mesh generator. If you checked the mesh over the aerofoil, you will find that, there are more than one cell in the empty direction.
The solution is easy, you can use extrudeMesh utility. Fortunately, there is a tutorial for this particular case. Please check wingMotion tutorial under pimpleDyMFoam tutorials directory.


Best wishes,
Hassan Kassem
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File Type: jpg aerfoil.jpg (100.4 KB, 21 views)
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Old   May 8, 2016, 09:46
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Quote:
Originally Posted by hk318i View Post
Hello,



This error mainly means that empty BC is used but the mesh isn’t 2D.
The problem is that you are trying to create 2D mesh using snappyHexMesh which is 3D mesh generator. If you checked the mesh over the aerofoil, you will find that, there are more than one cell in the empty direction.
The solution is easy, you can use extrudeMesh utility. Fortunately, there is a tutorial for this particular case. Please check wingMotion tutorial under pimpleDyMFoam tutorials directory.


Best wishes,
Hassan Kassem
Hello,
thank you for the reply. Anyway I forget to specify that this error appears after I used extrudeMesh.
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Old   May 8, 2016, 12:05
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Hi,

How many cells are there in the direction of extrusion? If it is not 1, then you will not be able to run a 2D problem and I suppose the issue of non-empty directions and edges would be present.

Cheers,
Antimony
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Old   May 8, 2016, 12:47
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Hassan Kassem
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Hello,

I checked your case again and it works fine with the extrudeMeshDict which is already included.
Attached Files
File Type: txt log.checkMesh.txt (3.4 KB, 8 views)
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Old   May 9, 2016, 04:33
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Quote:
Originally Posted by hk318i View Post
Hello,

I checked your case again and it works fine with the extrudeMeshDict which is already included.
Hello again,
I tried again and now it works. I don't know why earlier I have this error, probably I checked all the time step and it detects this error.
Thank you for the reply
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Old   April 5, 2018, 20:50
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Luís Tiago Ferreira Fernandes
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Hi all,

I'm having this problem and now I got confused. After snappyhexmesh I run checkmesh and get that error of the number of edges not aligned. But I get for the time steps of 0.001s and 0.002 which are defined by deltaT.
So you're saying that the checkmesh that matters is the one for "time = constant" ? And how can i use checkmesh for that time only?

Thanks
Luís
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