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checkMesh Errors after refineMesh

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Old   July 30, 2012, 21:39
Default checkMesh Errors after refineMesh
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Matthew Denno
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Hello,

I posted this question to the mesh utilities form a few days ago, but thought I would give it a shot here too as I think this section gets more traffic.

checkMesh Erros after refineMesh

I have a mesh that was created using snappyHexMesh that I am trying to refine using refineMesh, but after running refineMesh, checkMesh gives me errors. I am running an interFoam simulation and am trying to refine the mesh near the air/water interface. In order to use refineMesh, I first created a cellSet using topoSet based on the value of alpha and then used that to define which cells need to be refined. refineMesh completes without errors and based on visual inspection the correct locations seem to be refined. However, when I run checkMesh I get errors. My refineMeshDict and checkMesh output are below.

I have tried to use patchLocal coordinates and geometricCut instead, but neither fixed the problem (although the results were different). If I change the directions so that it doesn't refine in the normal direction, checkMesh does not give errors but the refinement is not what I need (i.e. not refined in the z direction).

I have also tried to visualize were the problems might be using foamToVTK but don't seem to be able to see the faces in paraFoam, I am guessing because maybe they are too small and spreadout.

At this point I am stuck. There don't seem to be very many input parameters to change for refineMesh, so I am not sure what to do next. Thoughts?

I have tried it in both 2.1.0 and 2.1.x with the same results.

refineMeshDict:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      refineMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
// Cells to refine; name of cell set
set c0;
 
// Type of coordinate system:
// - global : coordinate system same for every cell. Usually aligned with
//   x,y,z axis. Specify in globalCoeffs section below.
// - patchLocal : coordinate system different for every cell. Specify in
//   patchLocalCoeffs section below.
coordinateSystem global;
//coordinateSystem patchLocal;
 
// .. and its coefficients. x,y in this case. (normal direction is calculated
// as tan1^tan2)
globalCoeffs
{
    tan1 (1 0 0);
    tan2 (0 1 0);
}
 
patchLocalCoeffs
{
    patch outside;  // Normal direction is facenormal of zero'th face of patch
    tan1 (1 0 0);
}
 
// List of directions to refine
directions
(
    tan1   //x
    tan2   //y
    normal //z
);
 
// Whether to use hex topology. This will
// - if patchLocal: all cells on selected patch should be hex
// - split all hexes in 2x2x2 through the middle of edges.
useHexTopology  true;
 
// Cut purely geometric (will cut hexes through vertices) or take topology
// into account. Incompatible with useHexTopology
geometricCut    false;
 
// Write meshes from intermediate steps
writeMesh       false;
 
// ************************************************************************* //
checkMesh output:
Code:
hydro@Bass:rasWES-WithPier-Refined2$ checkMesh -time 0.001
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1.x                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : 2.1.x-2ddb0f183f86
Exec   : checkMesh -time 0.001
Date   : Jul 26 2012
Time   : 22:16:52
Host   : "Bass"
PID    : 5559
Case   : /home/hydro/OpenFOAM/hydro-2.1.0/run/wes/rasWES-WithPier-Refined2
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 = 0.001
 
Time = 0.001
 
Mesh stats
    points:           221480
    faces:            597334
    internal faces:   560780
    cells:            188271
    boundary patches: 6
    point zones:      0
    face zones:       0
    cell zones:       0
 
Overall number of cells of each type:
    hexahedra:     176891
    prisms:        1590
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     9790
 
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                  
    top                 2050     2271     ok (non-closed singly connected)  
    walls               19801    20838    ok (non-closed singly connected)  
    outlet              960      1055     ok (non-closed singly connected)  
    inlet               819      907      ok (non-closed singly connected)  
    bottom              1586     1757     ok (non-closed singly connected)  
    wes                 11338    11835    ok (non-closed singly connected)  
 
Checking geometry...
    Overall domain bounding box (-40 0 0) (40 6.33 30)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (5.55089e-16 -9.55142e-16 -1.45354e-15) OK.
    Max cell openness = 4.41608e-16 OK.
    Max aspect ratio = 4.53029 OK.
 ***Zero or negative face area detected.  Minimum area: 0
  <<Writing 4 zero area faces to set zeroAreaFaces
    Min volume = 0.000624369. Max volume = 0.13697.  Total volume = 12956.9.  Cell volumes OK.
    Mesh non-orthogonality Max: 149.508 average: 6.90896
   *Number of severely non-orthogonal faces: 2.
 ***Number of non-orthogonality errors: 46.
  <<Writing 48 non-orthogonal faces to set nonOrthoFaces
 ***Error in face pyramids: 66 faces are incorrectly oriented.
  <<Writing 33 faces with incorrect orientation to set wrongOrientedFaces
    Max skewness = 2.66863 OK.
    Coupled point location match (average 0) OK.
 
Failed 3 mesh checks.
 
End
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