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-   -   [blockMesh] Axi-symmetric blockmesh (https://www.cfd-online.com/Forums/openfoam-meshing/150377-axi-symmetric-blockmesh.html)

JFluid March 20, 2015 16:53
Axi-symmetric blockmesh
 
Hello,

I am trying to create an axisymmetric mesh with blockMesh. The mesher is giving me a warning about the non-panarity of faces ("The local face at ... the normal ... differs from the average normal ... by 5.18e-15"). The mesh appears to have generated, but the case will not run. Any help would be greatly appreciated. Here is my input file:

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                |                                                |
| \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox          |
|  \\    /  O peration    | Version:  2.3.1                                |
|  \\  /    A nd          | Web:      www.OpenFOAM.org                      |
|    \\/    M anipulation  |                                                |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version    2.0;
    format      ascii;
    class      dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
    (0.000 0.000 0.000)    // 0
    (368.000 0.000 0.000)  // 1
    (378.83092 0.000 0.000)  // 2
    (382.64092 0.000 0.000)  // 3
    (414.39092 0.000 0.000)  // 4
    (602.35092 0.000 0.000)  // 5
    (602.35092 0.20502 9.39576)  // 6
    (602.35092 -0.20502 9.39576) // 7
    (414.39092 0.20502 9.39576)  // 8
    (414.39092 -0.20502 9.39576) // 9
    (382.64092 0.09974 4.57091)  // 10
    (382.64092 -0.09974 4.57091) // 11
    (378.83092 0.09974 4.57091)  // 12
    (378.83092 -0.09974 4.57091) // 13
    (370.84000 0.20225 9.26879)  // 14
    (370.84000 -0.20225 9.26879) // 15
    (0.000 0.20225 9.26879)    // 16
    (0.000 -0.20225 9.26879)  // 17
);

edges
(
    // Due to sweeping 2.5 degrees
    arc 6 7 (602.35092 0.000 9.398)
    arc 8 9 (414.39092 0.000 9.398)
    arc 10 11 (382.64092 0.000 4.572)
    arc 12 13 (378.83092 0.000 4.572)
    arc 14 15 (370.84 0.000 9.271)
    arc 16 17 (0.000 0.000 9.271)

);

blocks
(
    hex (9 11 10 8 4 3 3 4) (30 1 40) simpleGrading (1 1 200)    // diffuser
);

boundary
(
    inlet
    {
        type patch;
        faces
        (
            (10 3 3 11)
        );
    }
    outlet
    {
        type patch;
        faces
        (
            (8 4 4 9)
        );
    }
    front
    {
        type wedge;
        faces
        (
            (4 9 11 3)
        );
    }

    back
    {
        type wedge;
        faces
        (
            (3 10 8 4)
        );
    }
    wall
    {
        type wall;
        faces
        (
            (11 9 8 10)
        );
    }
    axis
    {
        type empty;
        faces
        (
            (3 4 4 3)
        );
    }
);

mergePatchPairs
(
);

// ************************************************************************* //

wouter March 20, 2015 17:56
Hello JFluid,

I have very little experience with blockMesh but I had a simular problem and it was solved by increasing writePrecision in controlDict, so maybe it helps you as well

Best
Wouter

JFluid March 23, 2015 09:31
Wouter, thank you very much for the reply. I already had the writePrecision set to 12. But your post gave me an idea. I solved the problem by increasing the number of digits of precision in the spreadsheet that I used to generate the mesh. 8 digits after the decimal point worked.


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