[RebeccaWS]

Hi

I've been trying to generate a mesh for an internal flow problem. I have successfully generate the background mesh in blockMesh and extracted edges, but when I ran snappyHexMesh from the case directory I got the following error message:

 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
  Create time
   
  Create mesh for time = 0
   
  Read mesh in = 0.05 s
  --> FOAM Warning :
      From function entry::getKeyword(keyType&, Istream&)
      in file db/dictionary/entry/entryIO.C at line 77
      Reading /home/RWS/FlowrateCheck/10micronpore/system/snappyHexMeshDict
      found on line 31 the label 10
      expected either } or EOF
   
   
  --> FOAM FATAL IO ERROR:
  keyword castellatedMeshControls is undefined in dictionary "/home/RWS/FlowrateCheck/10micronpore/system/snappyHexMeshDict"
   
  file: /home/RWS/FlowrateCheck/10micronpore/system/snappyHexMeshDict from line 19 to line 34.
   
      From function dictionary::subDict(const word& keyword)
      in file db/dictionary/dictionary.C at line 479.
   
  FOAM exiting

I doublechecked my snappyHexMeshDict (please see below) but castellatedMeshControls is definitely defined in the code. Would someone be able to give me a pointer as to what I might be missing/doing wrong?

Many thanks

Reb

** My snappyHexMeshDict file **

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.0.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

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

// Which of the steps to run
castellatedMesh true;
snap            true;
addLayers       false;    // For now

// Geometry. Definition of all surfaces. All surfaces are of class
// searchableSurface.
// Surfaces are used
// - to specify refinement for any mesh cell intersecting it
// - to specify refinement for any mesh cell inside/outside/near
// - to 'snap' the mesh boundary to the surface
geometry
{
    10micronpore_custom_ascii.stl
    {
        type triSurfaceMesh;
        name flowdomain;
    }
};

// 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 100000;

    // 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 3000000;

    // 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 20;

    // 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 2;

    // Explicit feature edge refinement
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Specifies a level for any cell intersected by its edges.
    features
    (
        {
            file "10micronpore_custom_ascii.eMesh";
            level 0;
        }
    );

    // Surface based refinement
    // ~~~~~~~~~~~~~~~~~~~~~~~~

    // Specifies two levels for every surface. The first is the minimum level,
    // every cell intersecting a surface gets refined up to the minimum level.
    // The second level is the maximum level. Cells that 'see' multiple
    // intersections where the intersections make an
    // angle > resolveFeatureAngle get refined up to the maximum level.

    refinementSurfaces
    {
        "flowdomain_*"
          {
            level (8 9);    // Surface-wise min and max refinement level
          }
    }

    // Resolve sharp angles
    resolveFeatureAngle 180;

    // Region-wise refinement
    // ~~~~~~~~~~~~~~~~~~~~~~

    // Specifies refinement level for cells in relation to a surface. One of
    // three modes
    // - distance. 'levels' specifies per distance to the surface the
    //   wanted refinement level. The distances need to be specified in
    //   descending order.
    // - inside. 'levels' is only one entry and only the level is used. All
    //   cells inside the surface get refined up to the level. The surface
    //   needs to be closed for this to be possible.
    // - outside. Same but cells outside.

    refinementRegions
    {
    }

    // Mesh selection
    // ~~~~~~~~~~~~~~

    // After refinement patches get added for all refinementSurfaces and
    // all cells intersecting the surfaces get put into these patches. The
    // section reachable from the locationInMesh is kept.
    // NOTE: This point should never be on a face, always inside a cell, even
    // after refinement.
    locationInMesh (0.002 0.0 0.0);

    // 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 10;

    //- 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 10;

    //- Highly experimental and wip: number of feature edge snapping
    //  iterations. Leave out altogether to disable.
    //  Do not use here since mesh resolution too low and baffles present
    nFeatureSnapIter 10;
}

/*// Settings for the layer addition.
addLayersControls
{
    // Are the thickness parameters below relative to the undistorted
    // size of the refined cell outside layer (true) or absolute sizes (false).
    relativeSizes true;

    // Per final patch (so not geometry!) the layer information
    layers
    {
        "flowdomain_*"
        {
           nSurfaceLayers 4;
        }
    }

    // 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.
    //  is the thickness of the layer furthest away from the wall.
    //  See relativeSizes parameter.
    finalLayerThickness 0.5;

    //- 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 0.1;

    //- 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 17x! (didn't do anything in 17x)
    nGrow 0;

    // Advanced settings

    //- When not to extrude surface. 0 is flat surface, 90 is when two faces
    //  make straight angle.
    featureAngle 90;

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

    // Number of smoothing iterations of surface normals
    nSmoothSurfaceNormals 1;

    // Number of smoothing iterations of interior mesh movement direction
    nSmoothNormals 3;

    // 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 17x! 90 degrees corresponds to 130 in 17x.
    minMedianAxisAngle 90;


    // 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 50;
}*/

// Generic mesh quality settings. At any undoable phase these determine
// where to undo.

meshQualityControls
{
    //- Maximum non-orthogonality allowed. Set to 180 to disable.
    maxNonOrtho 65;

    //- Max skewness allowed. Set to <0 to disable.
    maxBoundarySkewness 3.5;
    maxInternalSkewness 2.5;

    //- Max concaveness allowed. Is angle (in degrees) below which concavity
    //  is allowed. 0 is straight face, <0 would be convex face.
    //  Set to 180 to disable.
    maxConcave 80;

    //- Minimum pyramid volume. Is absolute volume of cell pyramid.
    //  Set to a sensible fraction of the smallest cell volume expected.
    //  Set to very negative number (e.g. -1E30) to disable.
    minVol -1e-30;

    //- Minimum quality of the tet formed by the face-centre
    //  and variable base point minimum decomposition triangles and
    //  the cell centre. This has to be a positive number for tracking
    //  to work. Set to very negative number (e.g. -1E30) to
    //  disable.
    //     <0 = inside out tet,
    //      0 = flat tet
    //      1 = regular tet
    minTetQuality 1e-30;

    //- Minimum face area. Set to <0 to disable.
    minArea -1;

    //- Minimum face twist. Set to <-1 to disable. dot product of face normal
    //- and face centre triangles normal
    minTwist 0.02;

    //- minimum normalised cell determinant
    //- 1 = hex, <= 0 = folded or flattened illegal cell
    minDeterminant 0.001;

    //- minFaceWeight (0 -> 0.5)
    minFaceWeight 0.02;

    //- minVolRatio (0 -> 1)
    minVolRatio 0.01;

    //must be >0 for Fluent compatibility
    minTriangleTwist -1;

    // Advanced

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

// Advanced

// Flags for optional output
// 0 : only write final meshes
// 1 : write intermediate meshes
// 2 : write volScalarField with cellLevel for postprocessing
// 4 : write current intersections as .obj files
debug 0;


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

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

[RebeccaWS]

Hi

I still haven't been able to solve the problem. Confusing thing is that the I can't find anything I might have done wrong (syntax mistake, typos etc) in the lines mentioned in the error message (i.e. lines 19-34) in my blockMeshDict file, which are:

castellatedMesh true;  snap            true;
  addLayers       false;    // For now
   
  // Geometry. Definition of all surfaces. All surfaces are of class
  // searchableSurface.
  // Surfaces are used
  // - to specify refinement for any mesh cell intersecting it
  // - to specify refinement for any mesh cell inside/outside/near
  // - to 'snap' the mesh boundary to the surface
  geometry
  {
      10micronpore_custom_ascii.stl
      {
          type triSurfaceMesh;
          name flowdomain;

Also, the particular bit of code doesn't seem to be directly related to the keyword castellatedMeshControls being undefined. Coud someone please help??

Many thanks in advance

Rebecca

[onyir]

Hi Rebecca. I think the problem is having the stl file name starting with a number, instead of a letter.

Regards,

Ricardo.

[reza1980]

I have same problem ,If some body has soloution please let me know

[edalmau]

I didn't try to run SHM without some parameters on the castellated mesh, but you have MaxLocalCells & MaxLoadUnbalance with "//" at the beggining, they aren't recognized so maybe the snappyhexmesh didn't allow to mesh without it.

[DanAndrea87]

Hi everybody,
I had the same problem. After same tries I've solved it by adding a box (see the following code) just before "10micronpore_custom_ascii.stl".
It should looks like this:

geometry
{
    externalBox
    {
        type searchableBox;
        min (-0.3 -0.3 -0.4);
        max (0.3 0.3 0.4);
    }
    10micronpore_custom_ascii.stl
    {

etc...

So you have to create a box containing your entire geometry. That was the good news.
The bad news is that now I've another error:

--> FOAM FATAL IO ERROR: 
keyword scale is undefined in dictionary "/home/REDUCED_TRIGA_core/system/snappyHexMeshDict.geometry.polyMesh.regions"

file: /home/REDUCED_TRIGA_core/system/snappyHexMeshDict.geometry.polyMesh.regions from line 41 to line 77.

    From function dictionary::lookupEntry(const word&, bool, bool) const
    in file db/dictionary/dictionary.C at line 402.

FOAM exiting

Does someone have a solution?

[LucasCosta]

Someone have the answer for this problem?

[agustinvo]

Originally Posted by LucasCosta

Someone have the answer for this problem?

Hi Lucas,

as it is said before, the problem seems to appear when your STL filename starts with numbers. I just solved this problem by deleteing those numbers.