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Very simple case, weird blockMesh

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Old   October 16, 2013, 04:51
Default Very simple case, weird blockMesh
  #1
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Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 551
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Hi,

I want to create a box. My blockMesh code is:
Code:
convertToMeters 1;

vertices
(
    ( 581895  4785760  1038)
    ( 581895  4785760  1060)
    ( 581775  4785760  1060)
    ( 581775  4785760  1038)
    ( 581895  4785880  1038)
    ( 581895  4785880  1060)
    ( 581775  4785880  1060)
    ( 581775  4785880  1038)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (10 20 20) simpleGrading (10.0 1 1)
//    hex (0 1 2 3 4 5 6 7) (6 6 6) simpleGrading (10.0 1 1)
);

edges
(
);

boundary
(
    maxX
    {
        type patch;
        faces
        (
            (3 7 6 2)
        );
    }
    minZ
    {
        type patch;
        faces
        (
            (0 4 7 3)
        );
    }
    maxZ
    {
        type patch;
        faces
        (
            (2 6 5 1)
        );
    }
    minX
    {
        type patch;
        faces
        (
            (1 5 4 0)
        );
    }
    minY
    {
        type patch;
        faces
        (
            (0 3 2 1)
        );
    }
    maxY
    {
        type patch;
        faces
        (
            (4 5 6 7)
        );
    }
);

mergePatchPairs
(
);
You can see it very very simple. But I got errors:
Code:
Checking geometry...
    Overall domain bounding box (581775 4.78576e+06 1038) (581895 4.78588e+06 1060)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (4.04186e-17 3.46606e-17 0) OK.
 ***High aspect ratio cells found, Max aspect ratio: 2.11238e+201, number of cells 4000
  <<Writing 4000 cells with high aspect ratio to set highAspectRatioCells
    Minimum face area = 3.22979. Maximum face area = 36.  Face area magnitudes OK.
    Min volume = 2e-300. Max volume = 2e-300.  Total volume = 8e-297.  Cell volumes OK.
    Mesh non-orthogonality Max: 180 average: 180
 ***Number of non-orthogonality errors: 11200.
  <<Writing 11200 non-orthogonal faces to set nonOrthoFaces
 ***Error in face pyramids: 24000 faces are incorrectly oriented.
  <<Writing 12800 faces with incorrect orientation to set wrongOrientedFaces
    Max skewness = 4.32531e-09 OK.
    Coupled point location match (average 0) OK.

Failed 3 mesh checks.
Any ideas? Thanks.
Attached Files
File Type: c blockMeshDict.C (1.8 KB, 1 views)
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Old   October 16, 2013, 05:47
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  #2
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Hi sharonyue,

probably the problem is that you ordered the vertices wrong,
so your geometry looks somewhat like a sand clock.

To check this you can type paraFoam -block
and display your blockMesh file in paraview.

With this information you should be able to rearrange your vertices
correctly and get a satisfying blockMesh.

kind regards
Colin
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Old   October 16, 2013, 05:58
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  #3
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Dongyue Li
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Thanks man, you are rite. I should rearrange my vertices. woo!
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