[Counterdoc]

Hello,


I am trying to create a simulation for a duct. I already followed the tutorial from Tobi Holzmann on Youtube and created a combined stl in Salome that has the walls, inlet and outlet in it.

I also followed the tutorial to create the backgroundMesh / blockMesh.


When I run snappyHexMesh and only turn on the castallatedMesh the checkMesh is fine without any issues, but as soon as I run the case with snapping activated I have multiple mesh check errors.


I also tried to export a coarser and finer mesh from Salome to see how the results change. If I make it more coarse I have less errors.


Maybe someone could take a look at it. I think the issue is already in the mesh I export from Salome, but I have no idea to be honest.


What do you think about the mesh file? I uploaded it on my google drive:
https://drive.google.com/file/d/1CER...ew?usp=sharing



I can also share all my settings if needed.


This is the checkMesh result when castallatedMesh and snapping is active in snappyHexMesh:

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

Create mesh for time = 0

Check mesh...
    Enabling all (cell, face, edge, point) topology checks.
    Enabling all geometry checks.

Time = 0

Mesh stats
    points:           16122045
    faces:            43067034
    internal faces:   40796061
    cells:            13628462
    faces per cell:   6.15353
    boundary patches: 3
    point zones:      1
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     11854173
    prisms:        290583
    wedges:        0
    pyramids:      0
    tet wedges:    45
    tetrahedra:    0
    polyhedra:     1483661
    Breakdown of polyhedra by number of faces:
        faces   number of cells
            4   191202
            5   306498
            6   196869
            9   588074
           12   167246
           15   33688
           18   84

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Topological cell zip-up check OK.
    Face-face connectivity OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
                   Patch    Faces   Points  Surface topology  Bounding box
                   walls  1880080  2152825  ok (non-closed singly connected) (0.277328 -0.332841 -0.437397) (0.543067 0.202896 0.15)
                  outlet   283044   325371  ok (non-closed singly connected) (0.279425 0.00409194 -0.437397) (0.543067 0.202896 -0.265074)
                   inlet   107849   108453  ok (non-closed singly connected) (0.290787 -0.332841 0.149454) (0.483317 -0.194515 0.15)
                    ".*"  2270973  2582660      ok (closed singly connected) (0.277328 -0.332841 -0.437397) (0.543067 0.202896 0.15)


Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    No cellZones found.

Checking basic pointZone addressing...
               PointZone  PointsBoundingBox
            frozenPoints       0(1e+150 1e+150 1e+150) (-1e+150 -1e+150 -1e+150)

Checking geometry...
    Overall domain bounding box (0.277328 -0.332841 -0.437397) (0.543067 0.202896 0.15)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (1.48119e-15 9.69119e-15 -3.3278e-14) OK.
    Max cell openness = 1.18214e-15 OK.
    Max aspect ratio = 32.4546 OK.
    Minimum face area = 2.61988e-09. Maximum face area = 5.53432e-05.  Face area magnitudes OK.
    Min volume = 2.09625e-12. Max volume = 4.04742e-07.  Total volume = 0.0192226.  Cell volumes OK.
    Mesh non-orthogonality Max: 75.3513 average: 16.0218
   *Number of severely non-orthogonal (> 70 degrees) faces: 53.
    Non-orthogonality check OK.
  <<Writing 53 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
    Max skewness = 2.27597 OK.
    Coupled point location match (average 0) OK.
 ***Error in face tets: 94 faces with low quality or negative volume decomposition tets.
  <<Writing 94 faces with low quality or negative volume decomposition tets to set lowQualityTetFaces
    Min/max edge length = 2.94485e-06 0.00746041 OK.
   *There are 46297 faces with concave angles between consecutive edges. Max concave angle = 72.9746 degrees.
  <<Writing 46297 faces with concave angles to set concaveFaces
    Face flatness (1 = flat, 0 = butterfly) : min = 0.614082  average = 0.999016
   *There are 43 faces with ratio between projected and actual area < 0.8
    Minimum ratio (minimum flatness, maximum warpage) = 0.614082
  <<Writing 43 warped faces to set warpedFaces
    Cell determinant (wellposedness) : minimum: 8.52307e-10 average: 1.57495
 ***Cells with small determinant (< 0.001) found, number of cells: 173668
  <<Writing 173668 under-determined cells to set underdeterminedCells
 ***Concave cells (using face planes) found, number of cells: 404035
  <<Writing 404035 concave cells to set concaveCells
    Face interpolation weight : minimum: 0.00797014 average: 0.459465
 ***Faces with small interpolation weight (< 0.05) found, number of faces: 64
  <<Writing 64 faces with low interpolation weights to set lowWeightFaces
    Face volume ratio : minimum: 0.0216916 average: 0.811961
    Face volume ratio check OK.

Failed 4 mesh checks.

End

Best,
Marius

[wkernkamp]

The stl looks fine to me.


The number of cells 13+ million seems very high for this simple geometry. It is not an airplane. Easier and quicker to troubleshoot with less cells.


Are you requesting layers on the surface? If yes, turn it off for now.

[Counterdoc]

Thank you for the feedback. No, I am not using addLayers if you mean that. I changed some settings and reduced the number of cells. I am getting less errors, but still have issues. Could this just be a wrong config as the mesh itself looks good?


Current checkMesh:

Create time

Create mesh for time = 0

Check mesh...
    Enabling all (cell, face, edge, point) topology checks.
    Enabling all geometry checks.

Time = 0

Mesh stats
    points:           3865244
    faces:            10453102
    internal faces:   9947098
    cells:            3330659
    faces per cell:   6.12497
    boundary patches: 3
    point zones:      1
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     2869307
    prisms:        104547
    wedges:        0
    pyramids:      0
    tet wedges:    227
    tetrahedra:    1
    polyhedra:     356577
    Breakdown of polyhedra by number of faces:
        faces   number of cells
            4   73904
            5   53055
            6   44851
            9   136897
           12   39838
           15   7997
           18   35

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Topological cell zip-up check OK.
    Face-face connectivity OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
                   Patch    Faces   Points  Surface topology  Bounding box
                   walls   421003   486202  ok (non-closed singly connected) (0.277328 -0.33284 -0.437448) (0.543041 0.202946 0.15)
                  outlet    58080    67686  ok (non-closed singly connected) (0.279424 0.00381865 -0.437448) (0.543041 0.202946 -0.265026)
                   inlet    26921    27199  ok (non-closed singly connected) (0.290788 -0.33284 0.148975) (0.483297 -0.194507 0.150043)
                    ".*"   506004   579218      ok (closed singly connected) (0.277328 -0.33284 -0.437448) (0.543041 0.202946 0.150043)


Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    No cellZones found.

Checking basic pointZone addressing...
               PointZone  PointsBoundingBox
            frozenPoints       0(1e+150 1e+150 1e+150) (-1e+150 -1e+150 -1e+150)

Checking geometry...
    Overall domain bounding box (0.277328 -0.33284 -0.437448) (0.543041 0.202946 0.150043)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-1.40715e-15 6.12712e-15 4.49513e-15) OK.
    Max cell openness = 3.30839e-16 OK.
    Max aspect ratio = 15.7768 OK.
    Minimum face area = 6.1379e-08. Maximum face area = 5.56495e-05.  Face area magnitudes OK.
    Min volume = 2.93545e-11. Max volume = 4.07347e-07.  Total volume = 0.0193077.  Cell volumes OK.
    Mesh non-orthogonality Max: 80.5465 average: 10.321
   *Number of severely non-orthogonal (> 70 degrees) faces: 67.
    Non-orthogonality check OK.
  <<Writing 67 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
    Max skewness = 2.14612 OK.
    Coupled point location match (average 0) OK.
    Face tets OK.
    Min/max edge length = 7.23737e-05 0.00749861 OK.
   *There are 133 faces with concave angles between consecutive edges. Max concave angle = 89.4954 degrees.
  <<Writing 133 faces with concave angles to set concaveFaces
    Face flatness (1 = flat, 0 = butterfly) : min = 0.757178  average = 0.998955
   *There are 10 faces with ratio between projected and actual area < 0.8
    Minimum ratio (minimum flatness, maximum warpage) = 0.757178
  <<Writing 10 warped faces to set warpedFaces
    Cell determinant (wellposedness) : minimum: 5.15721e-08 average: 1.58641
 ***Cells with small determinant (< 0.001) found, number of cells: 106
  <<Writing 106 under-determined cells to set underdeterminedCells
 ***Concave cells (using face planes) found, number of cells: 91726
  <<Writing 91726 concave cells to set concaveCells
    Face interpolation weight : minimum: 0.0641447 average: 0.470851
    Face interpolation weight check OK.
    Face volume ratio : minimum: 0.0438647 average: 0.851465
    Face volume ratio check OK.

Failed 2 mesh checks.

End

[wkernkamp]

The offending cells are written to files. Might be a good idea to look to where things are going wrong.

[Counterdoc]

This is what the concaveCells set looks like.

[wkernkamp]

Very Odd. These cells look rectangular. Also, they are throughout the domain.


Can you have a closer look at a couple of individual cells. T spot exactly what is wrong with them.


How did you set up your run? Maybe start over from this example?
https://holzmann-cfd.com/community/t...meshing-a-pipe

[wkernkamp]

It might help to look at the tutorial iglooWithFridgesDirectionalRefinement.


look in system/snappyHexmesh and use that file in your own setup. Note you also need to substitute fvSolution and fvSchemes because thedisplacementSolver used to add layers requires it.

[Counterdoc]

Thanks for the tip with the tutorial files.

I managed to get down to 1 concaveCells and 17 faces with concave angles.


I also checked the VTK files and all of those cells and faces are on the edges of the model (see screenshot).



How can I get rid of those? As soon as I change any of the settings in snappyHexMeshDict it gets worse.


I am currently testing it without even adding the layers.



This is how my current snappyHexMeshDict looks like:

FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      snappyHexMeshDict;
}

castellatedMesh true;
snap            true;
addLayers       false;

geometry
{
    ductPipe
    {
        type triSurfaceMesh;
        file combined.stl;

        regions 
        {
            inlet   { name inlet; }
            outlet  { name outlet; }
            walls   { name walls; }
        }  
    }

};

// Settings for the castellatedMesh generation.
castellatedMeshControls
{

    // Refinement parameters
    // ~~~~~~~~~~~~~~~~~~~~~

    // If local number of cells is >= maxLocalCells on any processor
    // switches from from refinement followed by balancing
    // (current method) to (weighted) balancing before refinement.
    maxLocalCells 200000;

    // Overall cell limit (approximately). Refinement will stop immediately
    // upon reaching this number so a refinement level might not complete.
    // Note that this is the number of cells before removing the part which
    // is not 'visible' from the keepPoint. The final number of cells might
    // actually be a lot less.
    maxGlobalCells 4000000;

    // The surface refinement loop might spend lots of iterations refining just a
    // few cells. This setting will cause refinement to stop if <= minimumRefine
    // are selected for refinement. Note: it will at least do one iteration
    // (unless the number of cells to refine is 0)
    minRefinementCells 100;

    // Allow a certain level of imbalance during refining
    // (since balancing is quite expensive)
    // Expressed as fraction of perfect balance (= overall number of cells /
    // nProcs). 0=balance always.
    maxLoadUnbalance 0.10;


    // Number of buffer layers between different levels.
    // 1 means normal 2:1 refinement restriction, larger means slower
    // refinement.
    nCellsBetweenLevels 1;

    features
    (
        {
            file "combined.eMesh"; // Feature edges extracted earlier
            level 3;          // Feature refinement level
        }
    );

    refinementSurfaces
    {
        ductPipe
        {
            level (1 1);

            regions
            {
                inlet   { level (2 2); patchInfo { type patch; }}
                outlet  { level (2 2); patchInfo { type patch; }}
                walls   { level (2 3); patchInfo { type wall; inGroups (walls); }}
            }

            patchInfo
            {
                type wall;
                inGroups (walls);
            }
        }
        
    };

    refinementRegions
    {
        ductPipe
        {
            mode inside;
            levels ((0.01 3));
        }
    };

    resolveFeatureAngle 30;

    locationInMesh (0.4 0.04 -0.2);

    // Whether any faceZones (as specified in the refinementSurfaces)
    // are only on the boundary of corresponding cellZones or also allow
    // free-standing zone faces. Not used if there are no faceZones.
    allowFreeStandingZoneFaces true;

};

// Settings for the snapping.
snapControls
{
    //- Number of patch smoothing iterations before finding correspondence
    //  to surface
    nSmoothPatch 3;

    //- Relative distance for points to be attracted by surface feature point
    //  or edge. True distance is this factor times local
    //  maximum edge length.
    tolerance 4.0;

    //- Number of mesh displacement relaxation iterations.
    nSolveIter 10;

    //- Maximum number of snapping relaxation iterations. Should stop
    //  before upon reaching a correct mesh.
    nRelaxIter 15;

    // Feature snapping

        //- Number of feature edge snapping iterations.
        //  Leave out altogether to disable.
        nFeatureSnapIter 10;

        //- Detect (geometric only) features by sampling the surface
        //  (default=false).
        implicitFeatureSnap true;

        //- Use castellatedMeshControls::features (default = true)
        explicitFeatureSnap true;

        //- Detect points on multiple surfaces (only for explicitFeatureSnap)
        multiRegionFeatureSnap false;
};

// Controls for adding boundary layers
addLayersControls
{
    relativeSizes true;

    layers
    {
        walls
        {
            nSurfaceLayers 3;
        }
    }

    // Expansion factor for layer mesh
    expansionRatio 1.0;

    // Wanted thickness of final added cell layer. If multiple layers
    // is the thickness of the layer furthest away from the wall.
    // Relative to undistorted size of cell outside layer.
    // See relativeSizes parameter.
    finalLayerThickness 0.05;

    // Minimum thickness of cell layer. If for any reason layer
    // cannot be above minThickness do not add layer.
    // Relative to undistorted size of cell outside layer.
    minThickness 0.005;

    // If points get not extruded do nGrow layers of connected faces that are
    // also not grown. This helps convergence of the layer addition process
    // close to features.
    // Note: changed(corrected) w.r.t 1.7.x! (didn't do anything in 1.7.x)
    nGrow 0;

    // Advanced settings

    // When not to extrude surface. 0 is flat surface, 90 is when two faces
    // are perpendicular
    featureAngle 60;

    // At non-patched sides allow mesh to slip if extrusion direction makes
    // angle larger than slipFeatureAngle.
    slipFeatureAngle 30;

    // Maximum number of snapping relaxation iterations. Should stop
    // before upon reaching a correct mesh.
    nRelaxIter 5;

    // Number of smoothing iterations of surface normals
    nSmoothSurfaceNormals 3;

    // Number of smoothing iterations of interior mesh movement direction
    nSmoothNormals 10;

    // Smooth layer thickness over surface patches
    nSmoothThickness 10;

    // // Stop layer growth on highly warped cells
     maxFaceThicknessRatio 0.5;

    // // Reduce layer growth where ratio thickness to medial
    // // distance is large
     maxThicknessToMedialRatio 0.3;

    // // Angle used to pick up medial axis points
    // // Note: changed(corrected) w.r.t 1.7.x! 90 degrees corresponds to 130
    // // in 1.7.x.
     minMedialAxisAngle 90;


    //- Use displacementMotionSolver to shrink mesh
    meshShrinker displacementMotionSolver;

    //- Use laplacian for shrinking
    solver displacementLaplacian;

    displacementLaplacianCoeffs
    {
        diffusivity quadratic inverseDistance (walls);
    }


    // Create buffer region for new layer terminations
    nBufferCellsNoExtrude 0;


    // Overall max number of layer addition iterations. The mesher will exit
    // if it reaches this number of iterations; possibly with an illegal
    // mesh.
    nLayerIter 100;

    // Max number of iterations after which relaxed meshQuality controls
    // get used. Up to nRelaxIter it uses the settings in meshQualityControls,
    // after nRelaxIter it uses the values in meshQualityControls::relaxed.
    //nRelaxedIter 20;
};

// Mesh quality controls
meshQualityControls
{
    #include "meshQualityDict"

    // Optional : some meshing phases allow usage of relaxed rules.
    // See e.g. addLayersControls::nRelaxedIter.
    relaxed
    {
        //- Maximum non-orthogonality allowed. Set to 180 to disable.
        maxNonOrtho 65;
    }

    // Advanced

    //- Number of error distribution iterations
    nSmoothScale 4;
    //- amount to scale back displacement at error points
    errorReduction 0.75;
    
};

// Advanced

// Write flags
writeFlags
(
    scalarLevels
    layerSets
    layerFields     // write volScalarField for layer coverage
);


// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1e-6;

And my meshQualityDict:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2312                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      meshQualityDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

// Include defaults parameters from master dictionary
#includeEtc "caseDicts/meshQualityDict"

nSmoothScale 4;
errorReduction 0.75;

// Additional quality controls
maxNonOrtho 65;
maxBoundarySkewness 20;
maxInternalSkewness 4;
maxConcave 70;
minFlatness 0.5;
minVol 1e-15;
minTetQuality 1e-18;
minArea -1;
minTwist 0.02;
minDeterminant 0.001;
minFaceWeight 0.02;
minVolRatio 0.01;
minTriangleTwist -1;



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

Maybe someone with more experience could test my setup. No idea how to continue right now. And this is still a relatively easy geometry which is frustrating...

[Counterdoc]

I managed to get rid of the concaveCells by increasing the resolveFeatureAngle to 60.

There are now 8 concave angles left. I tried to run simpleFoam and this is how my residuals look like:

[AtoHM]

That's not good.


You seem to focus on concave metric, what is skewness and nonOrthogonality in this case?


More hints:
- why do you have implicitFeatureSnap and explicitFeatureSnap active? Its either one or the other. I always mesh with the default. Don't know what snappy does if both are on.
- increase cellsBetweenLevels to 2, 3 or 4. Heads up: this WILL increase the size of the mesh. But it's usually a good way to improve the mesh near walls if the wall cell level is higher than in the surrounding mesh. It becomes even more important if you want to use layers on these faces.

[Counterdoc]

I already disabled implicitFeatureSnap in the last run. You are right, it should only be one.


This is what the latest checkMesh looks like.

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2312                                  |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : _1d8f0d55f7-20231221 OPENFOAM=2312 version=v2312
Arch   : "LSB;label=32;scalar=64"
Exec   : checkMesh -allGeometry -allTopology -writeSets vtk
Date   : May 19 2024
Time   : 08:52:20
Host   : MacBook-Pro.fritz.box
PID    : 30583
I/O    : uncollated
Case   : /Users/marius.erlenbruch/Downloads/CFD-Openfoam/Radiator-coarse-2
nProcs : 1
trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 5, maxFileModificationPolls 20)
allowSystemOperations : Allowing user-supplied system call operations

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

Create mesh for time = 0

Check mesh...
    Enabling all (cell, face, edge, point) topology checks.
    Enabling all geometry checks.
    Reconstructing and writing vtk representation of all faceSets and cellSets.

Time = 0

Mesh stats 
    points:           401336
    faces:            1177231
    internal faces:   1145538
    cells:            390387
    faces per cell:   5.94991
    boundary patches: 3
    point zones:      1
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     375621
    prisms:        6760
    wedges:        0
    pyramids:      0
    tet wedges:    86
    tetrahedra:    2
    polyhedra:     7918
    Breakdown of polyhedra by number of faces:
        faces   number of cells
            4   4699
            5   3219

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Topological cell zip-up check OK.
    Face-face connectivity OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
                   Patch    Faces   Points  Surface topology  Bounding box
                   walls    26374    30555  ok (non-closed singly connected) (0.277333 -0.332837 -0.437441) (0.543034 0.202975 0.15)
                  outlet     3620     4296  ok (non-closed singly connected) (0.279424 0.00407739 -0.437441) (0.543034 0.202975 -0.265192)
                   inlet     1699     1763  ok (non-closed singly connected) (0.290792 -0.332837 0.14946) (0.483291 -0.194518 0.15)
                    ".*"    31693    36196      ok (closed singly connected) (0.277333 -0.332837 -0.437441) (0.543034 0.202975 0.15)


Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    No cellZones found.

Checking basic pointZone addressing...
               PointZone  PointsBoundingBox
            frozenPoints       0(1e+150 1e+150 1e+150) (-1e+150 -1e+150 -1e+150)

Checking geometry...
    Overall domain bounding box (0.277333 -0.332837 -0.437441) (0.543034 0.202975 0.15)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-1.78687e-17 2.02728e-16 -2.22045e-16) OK.
    Max cell openness = 3.00327e-16 OK.
    Max aspect ratio = 5.32817 OK.
    Minimum face area = 2.2764e-06. Maximum face area = 4.12514e-05.  Face area magnitudes OK.
    Min volume = 4.22218e-09. Max volume = 8.98825e-08.  Total volume = 0.0193022.  Cell volumes OK.
    Mesh non-orthogonality Max: 60.4705 average: 3.4999
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 1.76827 OK.
    Coupled point location match (average 0) OK.
    Face tets OK.
    Min/max edge length = 0.000237348 0.0090701 OK.
   *There are 8 faces with concave angles between consecutive edges. Max concave angle = 51.7665 degrees.
  <<Writing 8 faces with concave angles to set concaveFaces
    Face flatness (1 = flat, 0 = butterfly) : min = 0.85528  average = 0.999394
    All face flatness OK.
    Cell determinant (wellposedness) : minimum: 0.0185579 average: 0.950219
    Cell determinant check OK.
    Concave cell check OK.
    Face interpolation weight : minimum: 0.157128 average: 0.494249
    Face interpolation weight check OK.
    Face volume ratio : minimum: 0.118938 average: 0.969777
    Face volume ratio check OK.

Mesh OK.

End

[Counterdoc]

Originally Posted by AtoHM

That's not good.


You seem to focus on concave metric, what is skewness and nonOrthogonality in this case?


More hints:
- why do you have implicitFeatureSnap and explicitFeatureSnap active? Its either one or the other. I always mesh with the default. Don't know what snappy does if both are on.
- increase cellsBetweenLevels to 2, 3 or 4. Heads up: this WILL increase the size of the mesh. But it's usually a good way to improve the mesh near walls if the wall cell level is higher than in the surrounding mesh. It becomes even more important if you want to use layers on these faces.

I tried increasing cellsBetweenLevels but the checkMesh stays the same - which is plausible because I only used the same cellLevels over all regions and now span from 1-3 for example.



Another issue I have is on the edges:

Removing mesh beyond surface intersections
------------------------------------------

Setting cellZones according to locationsInMesh:
Location : (0.4 0.05 -0.25)
    cellZone : none

For cellZone none found point (0.4 0.05 -0.25) in global region 1 out of 2 regions.
--> FOAM Warning :
    From void Foam::meshRefinement::nearestFace(const Foam::labelUList &, const Foam::bitSet &, autoPtr<Foam::mapDistribute> &, Foam::labelList &, const Foam::label) const
    in file meshRefinement/meshRefinement.C at line 515
    Did not visit some faces, e.g. face 0 at (0.293269 -0.344904 -0.158424)
Keeping all cells containing inside points
Selected for keeping : 124570 cells.
Edge intersection testing:
    Number of edges             : 427281
    Number of edges to retest   : 46140
    Number of intersected edges : 51513