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zeroVolumeCells
  • atypicalguy September 2012
    Hello All,

    I exported my case to OpenFoam from Engrid, but when I run checkMesh it fails with a floating point exception after writing zeroVolumeCells. I have checked the surface mesh in enGrid and it is OK. Does anyone know how to get rid of the zero volume cells? I have run create/improve volume mesh in enGrid many times without benefit.

    Also, running "delete bad aspect ratio cells" does not appear to work on my mesh, though checkMesh seems to not mind as much.

    Thanks,
    Karl

    (OF:1.6-ext Opt) caelinux@karl-OF:OFtest2$ checkMesh
    /*---------------------------------------------------------------------------*\
    | ========= | |
    | \\ / F ield | OpenFOAM Extend Project: Open source CFD |
    | \\ / O peration | Version: 1.6-ext |
    | \\ / A nd | Web: www.extend-project.de |
    | \\/ M anipulation | |
    \*---------------------------------------------------------------------------*/
    Build : 1.6-ext-30132395b0df
    Exec : checkMesh
    Date : Sep 02 2012
    Time : 15:25:53
    Host : karl-OF
    PID : 25684
    Case : /home/caelinux/OpenFOAM/caelinux-1.6-ext/run/OFtest2
    nProcs : 1
    SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
    Create time

    Create polyMesh for time = 0


    From function void polyMesh::initMesh()
    in file meshes/polyMesh/polyMeshInitMesh.C at line 82
    Truncating neighbour list at 7014686 for backward compatibility
    Time = 0

    Mesh stats
    all points: 1351889
    live points: 1351889
    all faces: 7261298
    live faces: 7261298
    internal faces: 7014686
    cells: 2978166
    boundary patches: 9
    point zones: 0
    face zones: 0
    cell zones: 0

    Overall number of cells of each type:
    hexahedra: 0
    prisms: 2363320
    wedges: 0
    pyramids: 0
    tet wedges: 0
    tetrahedra: 614846
    polyhedra: 0

    Checking topology...
    Boundary definition OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

    Checking patch topology for multiply connected surfaces ...
    Patch Faces Points Surface topology
    Bottom 31348 17150 ok (non-closed singly connected)
    BottomTip 5922 3286 ok (non-closed singly connected)
    Far 372 209 ok (non-closed singly connected)
    Leading 98911 52157 ok (non-closed singly connected)
    LeadingTip 61827 31506 ok (non-closed singly connected)
    Sym 9908 6439 ok (non-closed singly connected)
    Tip 1268 707 ok (non-closed singly connected)
    Top 31172 17113 ok (non-closed singly connected)
    TopTip 5884 3282 ok (non-closed singly connected)

    Checking geometry...
    This is a 3-D mesh
    Overall domain bounding box (-8.42746e-07 -3.21339 -3.21528) (3.18778 3.2111 3.20832)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Mesh (non-empty, non-wedge) dimensions 3
    Boundary openness (-6.63691e-15 5.14825e-18 -5.31685e-19) Threshold = 1e-06 OK.
    ***High aspect ratio cells found, Max aspect ratio: 3.4023e+06, number of cells 45848 Threshold = 1000
    Writing 45848 cells with high aspect ratio to set highAspectRatioCells
    ***Zero or negative face area detected. Minimum area: 0
    Writing 186 zero area faces to set zeroAreaFaces
    ***Zero or negative cell volume detected. Minimum negative volume: -2.75184e-06, Number of negative volume cells: 235998
    Writing 235998 zero volume cells to set zeroVolumeCells
    Floating point exception
  • atypicalguy September 2012
    I re-exported and tried it with 2.1.0 and the checkMesh completed. It has a few fewer faces now (?). Anyway the checkMesh crash is fixed. Apparently I have some orientation problems though...

    /*---------------------------------------------------------------------------*\
    | ========= | |
    | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
    | \\ / O peration | Version: 2.1.0 |
    | \\ / A nd | Web: www.OpenFOAM.org |
    | \\/ M anipulation | |
    \*---------------------------------------------------------------------------*/
    Build : 2.1.0-0bc225064152
    Exec : checkMesh
    Date : Sep 02 2012
    Time : 16:11:42
    Host : "karl-OF"
    PID : 28747
    Case : /home/caelinux/OpenFOAM/caelinux-2.1.0/run/OFtest2
    nProcs : 1
    sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
    fileModificationChecking : Monitoring run-time modified files using timeStampMaster
    allowSystemOperations : Disallowing user-supplied system call operations

    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
    Create time

    Create polyMesh for time = 0

    Time = 0

    Mesh stats
    points: 1351891
    faces: 7261024
    internal faces: 7014412
    cells: 2978029
    boundary patches: 9
    point zones: 0
    face zones: 0
    cell zones: 0

    Overall number of cells of each type:
    hexahedra: 0
    prisms: 2363320
    wedges: 0
    pyramids: 0
    tet wedges: 0
    tetrahedra: 614709
    polyhedra: 0

    Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

    Checking patch topology for multiply connected surfaces ...
    Patch Faces Points Surface topology
    Bottom 31348 17150 ok (non-closed singly connected)
    BottomTip 5922 3286 ok (non-closed singly connected)
    Far 372 209 ok (non-closed singly connected)
    Leading 98911 52157 ok (non-closed singly connected)
    LeadingTip 61827 31506 ok (non-closed singly connected)
    Sym 9908 6439 ok (non-closed singly connected)
    Tip 1268 707 ok (non-closed singly connected)
    Top 31172 17113 ok (non-closed singly connected)
    TopTip 5884 3282 ok (non-closed singly connected)

    Checking geometry...
    Overall domain bounding box (-8.42746e-07 -3.21339 -3.21528) (3.18778 3.2111 3.20832)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (-6.57697e-15 9.32974e-18 -1.46016e-17) OK.
    ***High aspect ratio cells found, Max aspect ratio: 2.42032e+196, number of cells 235945
    <<Writing 235945 cells with high aspect ratio to set highAspectRatioCells<br /> ***Zero or negative face area detected. Minimum area: 0
    <<Writing 186 zero area faces to set zeroAreaFaces<br /> Min volume = 1.66667e-300. Max volume = 0.176511. Total volume = 68.1197. Cell volumes OK.
    Mesh non-orthogonality Max: 179.999 average: 42.4236
    *Number of severely non-orthogonal faces: 28419.
    ***Number of non-orthogonality errors: 799193.
    <<Writing 827612 non-orthogonal faces to set nonOrthoFaces<br /> ***Error in face pyramids: 1177449 faces are incorrectly oriented.
    <<Writing 824544 faces with incorrect orientation to set wrongOrientedFaces<br /> ***Max skewness = 32405.7, 49993 highly skew faces detected which may impair the quality of the results
    <<Writing 49993 skew faces to set skewFaces<br /> Coupled point location match (average 0) OK.

    Failed 5 mesh checks.

    End