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Tetragramm September 22, 2012 16:00

mesh causing problems with convergence
 
1 Attachment(s)
I'm having problems with my mesh causing divergence. I'm trying to replicate the results in this PDF here but the mesh I've created has issues are causing simpleFoam to diverge. For some reason, the solution is only diverging at higher angles of attack.

I've put together a set of pictures showing the problem and my geometry. They are located here. For some reason, all along the join between the four hex blocks, the solution diverges. The most extreme example is the portion pictured in the album.

I'm not sure if the non-ortho faces that checkMesh finds are the source of the problem. There are some right at the wingtip, where the most extreme divergence is, but the divergence continues all the way out, but there are no non-ortho faces that far out.

I'm hoping that one of you can tell me how to fix the problem without having to re-do the whole blockMesh file. Or, if you say that's not possible, to give me recommendations on how to make this geometry without causing bad cells and faces in the mesh. I'd like any suggestions to keep in mind that I will be changing things like airfoils and aspect ratio, so it should be automation friendly.

Thank you for you help.

I've attached my blockMesh file and this is my checkMesh file
Code:

/*---------------------------------------------------------------------------*\
| =========                |                                                |
| \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox          |
|  \\    /  O peration    | Version:  2.1.1                                |
|  \\  /    A nd          | Web:      www.OpenFOAM.org                      |
|    \\/    M anipulation  |                                                |
\*---------------------------------------------------------------------------*/
Build  : 2.1.1-221db2718bbb
Exec  : checkMesh
Date  : Sep 22 2012
Time  : 13:54:28
Host  : "Heterodyne"
PID    : 2781
Case  : /home/tetragramm/OpenFOAM/0012
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:          4040101
    faces:            12040000
    internal faces:  11920000
    cells:            4000000
    boundary patches: 4
    point zones:      0
    face zones:      0
    cell zones:      0

Overall number of cells of each type:
    hexahedra:    3960000
    prisms:        40000
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    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                 
    movingWall          40000    40001    ok (non-closed singly connected) 
    fixedWalls          40000    40001    ok (non-closed singly connected) 
    symmetricWall      40000    40400    ok (non-closed singly connected) 
    allAround          0        0        ok (empty)                       

Checking geometry...
    Overall domain bounding box (-2.59808 -2.84808 0) (2.59808 2.34808 3)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (-2.07313e-15 -5.50671e-15 5.79448e-15) OK.
    Max cell openness = 1.74778e-15 OK.
    Max aspect ratio = 149.528 OK.
    Minumum face area = 4.19645e-07. Maximum face area = 0.00338268.  Face area magnitudes OK.
    Min volume = 1.46671e-09. Max volume = 7.5958e-05.  Total volume = 30.7017.  Cell volumes OK.
    Mesh non-orthogonality Max: 86.9482 average: 28.9597
  *Number of severely non-orthogonal faces: 24795.
    Non-orthogonality check OK.
  <<Writing 24795 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
 ***Max skewness = 11.086, 9003 highly skew faces detected which may impair the quality of the results
  <<Writing 9003 skew faces to set skewFaces
    Coupled point location match (average 0) OK.

Failed 1 mesh checks.

End



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