snappyHexMeshDict

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2506                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

// Type of mesh generation:
//  - castellated (default)
//  - castellatedBufferLayer
//type            castellatedBufferLayer;


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


// Optional: single region surfaces get patch names according to
//           surface only. Multi-region surfaces get patch name
//           surface "_ "region. Default is true
// singleRegionName false;

// Optional: avoid patch-face merging. Allows mesh to be used for
//           refinement/unrefinement
// mergePatchFaces    false; // default true

// Optional: allow patch-face merging even if differing patches. This avoids
// splitting boundary faces and might benefit layer coverage.
// (Note: only applicable if mergePatchFaces true)
// mergeAcrossPatches   true;   // default false

// Optional: preserve all generated patches. Default is to remove
//          zero-sized patches.
// keepPatches true;


// Geometry. 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
{
    box1x1x1
    {
        type box;
        min  (1.5 1 -0.5);
        max  (3.5 2 0.5);
    }

    // Shell for directional refinement
    wakeBox
    {
        type box;
        min  (1.5 1 -0.5);
        max  (3.5 2 0.5);
    }

    sphere.stl
    {
        type triSurfaceMesh;

        //tolerance   1E-5;   // optional:non-default tolerance on intersections
        //maxTreeDepth 10;    // optional:depth of octree. Decrease only in case
                              // of memory limitations.

        // Per region the patchname. If not provided will be <surface>_<region>.
        // Note: this name cannot be used to identity this region in any
        //       other part of this dictionary; it is only a name
        //       for the combination of surface+region (which is only used
        //       when creating patches)
        regions
        {
            secondSolid
            {
                name mySecondPatch;
            }
        }
    }

    sphere2
    {
        type    sphere;
        centre  (1.5 1.5 1.5);
        radius  1.03;
    }
};


// Settings for the castellatedMesh generation.
castellatedMeshControls
{

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

    // If local number of cells is >= maxLocalCells on any processor
    // algorithm switches from refinement followed by (weighted) balancing
    // to (weighted) balancing followed by 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 2000000;

    // The surface refinement loop might spend lots of iterations refining just
    // a few cells. This setting will cause refinement to stop if
    // <= minRefinementCells cells are selected for refinement. Note: it will
    // at least do one iteration unless
    //  a: the number of cells to refine is 0
    //  b: minRefinementCells = -1. This is a special value indicating
    //     no refinement.
    minRefinementCells 0;

    // 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. Can be triggered by using maxCellUnbalance
    maxLoadUnbalance 0.10;

    // Optional absolute unbalance start trigger. Used to avoid balancing
    // in first refinement iterations since balancing is expensive for
    // high core counts
    // The trigger value is used for two checks:
    // a: if on any processor the number of new added cells <= maxCellUnbalance
    //    the balancing is skipped
    // b: if on any processor the value 
    //    (new cell count of proc - idealCellCount) <= maxCellUnbalance
    //    the balancing is skipped
    // Set to -1 to deactivate
    //maxCellUnbalance 200000;

    // Optional forcing balancing after the mesh is completely refined
    //balanceAtEnd     false;

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


    // Explicit feature edge refinement
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    // Specifies a level for any cell intersected by explicitly provided
    // edges.
    // This is a featureEdgeMesh, read from constant/triSurface for now.
    // Specify 'levels' in the same way as the 'distance' mode in the
    // refinementRegions (see below). The old specification
    //      level   2;
    // is equivalent to
    //      levels  ((0 2));

    features
    (
        //{
        //    file "someLine.eMesh";
        //    //level 2;        // Have level 2 for all cells intersected
        //                      // by feature.
        //    levels ((0.1 2)); // Have level 2 for all cells within
        //                      // 0.1 of feature.
        //}
    );


    // 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
    {
        sphere.stl
        {
            // Surface-wise min and max refinement level
            level (2 2);

            // Optional region-wise level specification
            regions
            {
                secondSolid
                {
                    level (3 3);
                }
            }

            // Optional specification of patch type (default is wall). No
            // constraint types (cyclic, symmetry) etc. are allowed.
            patchInfo
            {
                type patch;
                inGroups (meshedPatches);
            }


            //- Optional increment (on top of max level) in small gaps
            //gapLevelIncrement 2;

            //- Optional angle to detect small-large cell situation
            //  perpendicular to the surface. Is the angle of face w.r.t.
            //  the local surface normal. Use on flat(ish) surfaces only.
            //  Otherwise leave out or set to negative number.
            //perpendicularAngle 10;

            //- Optional faceZone and (for closed surface) cellZone with
            //  how to select the cells that are in the cellZone
            //  (inside / outside / specified insidePoint)
            //  The orientation of the faceZone is
            //  - if on cellZone(s) : point out of (minimum) cellZone
            //  - if freestanding   : oriented according to surface

            //faceZone sphere;
            //cellZone sphere;
            //cellZoneInside inside;    // outside/insidePoint
            //insidePoint    (1 1 1);   // if (cellZoneInside == insidePoint)
            //   or alternative multiple insidePoints:
            //insidePoints   ((1 1 1));   // if (cellZoneInside == insidePoint)

            //- Optional specification of what to do with faceZone faces:
            //      internal : keep them as internal faces (default)
            //      baffle   : create baffles from them. This gives more
            //                 freedom in mesh motion
            //      boundary : create free-standing boundary faces (baffles
            //                 but without the shared points)
            //faceType baffle;

            //- Optional automatic gap refinement. See section in
            //  refinementRegions ('gapLevel', 'gapMode')

            //- Optional removal of cells in thin gaps.
            //  Block any gap (opposite surfaces or opposite disconnected region
            //  of surface):
            //  - thinner than 2*blockcellsize where blockcellsize
            //    is the size of a cell at blockLevel
            //  Note: it does not relate to the refinement level of the cells
            //        it 'blocks'/deletes.
            //blockLevel 10;

            //- Optional early detection of connections between inside and
            //  outside locations. Default is only after all refinement has
            //  been done.
            //leakLevel 10;

            // Additional refinement for regions of high curvature. Expressed
            // (bit similar to gapLevel) as:
            // - number of cells per radius of curvature. (usually 1 is
            //   good enough)
            // - starting cell level? Not used at the moment.
            // - maximum cell level. This can be smaller or larger than the
            //   max 'surface' level
            // - minumum curvature radius to ignore (expressed as a cell level).
            //   This can be used to avoid detecting small sharp surface
            //   features. Set to -1 to ignore.
            //   (sometimes you want more refinement than sharp features since
            //    these can be done with feature edge snapping (so can leave
            //    level (0 0))
            //curvatureLevel (10 0 10 -1);

            // Optional disabling of buffer layer addition (if switched on by
            // type = castellatedBufferLayer)
            addBufferLayers false;
        }
    }

    // Feature angle:
    // - used if min and max refinement level of a surface differ
    // - used if feature snapping (see snapControls below) is used
    resolveFeatureAngle 30;

    //- Optional increment (on top of max level) in small gaps
    //gapLevelIncrement 2;


    // Planar angle:
    // - used to determine if surface normals
    //   are roughly the same or opposite. Used
    //      - in proximity refinement
    //      - to decide when to merge free-standing baffles
    //        (if e.g. running in surfaceSimplify mode set this to 180 to
    //         merge all baffles)
    //      - in snapping to avoid snapping to nearest on 'wrong' side
    //        of thin gap
    //
    // If not specified same as resolveFeatureAngle
    planarAngle 30;


    // 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
    //   increasing 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
    {
        box1x1x1
        {
            mode inside;
            levels ((1.0 4));
        }
        //sphere.stl
        //{
        //    mode inside;
        //    levels ((1.0 4));
        //    // Optional override of uniform refinement level such
        //    // that in small gaps we're getting more cells.
        //    // The specification is
        //    //  - numGapCells : minimum number of cells in the gap
        //    //                  (usually >3; lower than this might not
        //    //                   resolve correctly)
        //    //  - minLevel    : min refinement level at which to kick in
        //    //  - maxLevel    : upper refinement level (to avoid refinement
        //    //                  continuing on a single extraneous feature)
        //    // All three settings can be overridden on a surface by
        //    // surface basis in the refinementSurfaces section.
        //    gapLevel (<numGapCells> <minLevel> <maxlevel>);
        //    // Optional: when doing the gapLevel refinement directly remove
        //    //           based on orientation w.r.t. gap. This limits the
        //    //           amount of cells before doing the 'locationInMesh'
        //    //           cell selection. Default is 'mixed' i.e. keep cells
        //    //           whilst doing the gap-level refinement.
        //    //gapMode inside;  // inside/outside/mixed
        //    //gapSelf false;   // ignore gaps in same surface
        //}

        //wakeBox
        //{
        //    mode        inside;
        //    // Dummy base level
        //    levels      ((10000 0));
        //
        //    // Optional directional refinement (after all other refinement)
        //    // Directional refinement
        //    // for all cells according to 'mode' ('inside' or 'outside';
        //    // 'distance' not supported) and within certain range. E.g.
        //    //  - for all cells with level 2-5
        //    //  - do one split in x direction
        //    levelIncrement  (2 5 (1 0 0));
        //
        //    // Note
        //    // - ignores 'levels' and gap* settings.
        //    // - the cellLevel/pointLevels files are no longer consistent
        //    //   with the mesh, the resulting mesh is no longer compatible
        //    //   with e.g. dynamic refinement/unrefinement.
        //    // - cellLevel will include any directional refinement
        //    //   (i.e. it will be the maximum of all three directions)
        //}

        //wakeBox
        //{
        //    mode        inside;
        //    // Dummy base level
        //    levels      ((10000 0));
        //
        //    // Optional directional refinement (after all other refinement)
        //    // Directional refinement
        //    // for all cells according to 'mode' ('inside' or 'outside';
        //    // 'distance' not supported) and within certain range. E.g.
        //    //  - for all cells with level 2-5
        //    //  - do one split in x direction
        //    levelIncrement  (2 5 (1 0 0));
        //
        //    // Note
        //    // - ignores 'levels' and gap* settings.
        //    // - the cellLevel/pointLevels files are no longer consistent
        //    //   with the mesh, the resulting mesh is no longer compatible
        //    //   with e.g. dynamic refinement/unrefinement.
        //    // - cellLevel will include any directional refinement
        //    //   (i.e. it will be the maximum of all three directions)
        //
        //    // Optional directional expansion-ratio smoothing (after all
        //    // refinement). This will try to smooth out edge/cell size jumps
        //    // Specify smoothing direction and number of iterations
        //    smoothDirection     (1 0 0);
        //    // Smoothing of expansion ratio
        //    nSmoothExpansion    100;
        //    // Smoothing of positions
        //    nSmoothPosition     100;
        //}
    }



    // Optionally limit refinement in geometric region. This limits all
    // refinement (from features, refinementSurfaces, refinementRegions)
    // in a given geometric region. The syntax is exactly the same as for the
    // refinementRegions; the cell level now specifies the upper limit
    // for any cell. (a special setting is cell level -1 which will remove
    // any cells inside the region). Note that it does not override the
    // refinement constraints given by the nCellsBetweenLevels setting.
    limitRegions
    {
    }


    // 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 location(s)InMesh is kept.
    // NOTE: This point should never be on a face, always inside a cell, even
    // after refinement.
    //
    // There are two different ways of specifying the regions to keep:
    // 1. a single locationInMesh. This is the unzoned part of the mesh.
    //    All the 'zoned' surfaces are marked as such
    //    in the refinementSurfaces with the faceZone and cellZone keywords.
    //    It is illegal to have the locationInMesh inside a surface for which
    //    a cellZone is specified.
    //
    // or
    //
    // 2. multiple locationsInMesh, with per location the name of the cellZone.
    //    This uses walking to determine zones and automatically creates
    //    faceZones on the outside of cellZones. The special name 'none' is
    //    used to indicate the unzoned/background part of the mesh.


        // Ad 1. Specify a single location and how to treat faces inbetween
        //       cellZones
        locationInMesh (5 0.28 0.43);

        // Whether any faceZones (as specified in the refinementSurfaces)
        // are only on the boundary of corresponding cellZones.
        // Not used if there are no faceZones. The behaviour has changed
        // with respect to previous versions:
        //  true  : all intersections with surface are put in faceZone
        //          (same behaviour as before)
        //  false : depending on the type of surface intersected:
        //      - if intersecting surface has faceZone only (so no cellZone)
        //        leave in faceZone (so behave as if set to true) (= changed
        //        behaviour)
        //      - if intersecting surface has faceZone and cellZone
        //        remove if inbetween same cellZone or if on boundary
        //        (same behaviour as before)
        allowFreeStandingZoneFaces true;



        // 2. Specify multiple locations with optional cellZones for the
        //    regions (use cellZone "none" to specify the unzoned cells)
        //    FaceZones are automatically constructed from the
        //    names of the cellZones: <cellZoneA> _to_ <cellZoneB>
        //    where the cellZoneA is the lowest numbered cellZone (non-cellZone
        //    cells are in a special region called "none" which is always
        //    last).

        locationsInMesh
        (
            ((-0.09 -0.039 -0.049)  bottomAir)  // cellZone 0
            ((-0.09 0.009 -0.049)   topAir)     // cellZone 1
            ((-0.09 0.001 -0.049)   leftSolid)  // cellZone 2
            ((0.02  0.001 -0.049)   rightSolid) // cellZone 3
            ((-0.001 -0.039 0.0015) heater)     // cellZone 4
        );

        // Per synthesised faceZone name the faceType and type of baffles to
        // create
        faceZoneControls
        {
            bottomAir_to_heater
            {
                // Optional specification of patch type (default is wall). No
                // constraint types (cyclic, symmetry) etc. are allowed.
                patchInfo
                {
                    type patch;
                    inGroups (patchPatches);
                }
                faceType baffle;
            }
        }



    // Optional locations that should not be reachable from
    // location(s)InMesh
    locationsOutsideMesh ((100 100 100));

    // Optional: do not remove cells likely to give snapping problems
    // handleSnapProblems false;

    // Optional: switch off topological test for cells to-be-squashed
    //           and use geometric test instead
    //useTopologicalSnapDetection false;

    // Optional: do not refine surface cells with opposite faces of
    //           differing refinement levels
    //interfaceRefine false;

    // Optional: use an erosion instead of region assignment to allocate
    //           left-over cells to the background region (i.e. make cellZones
    //           consistent with the intersections of the surface).
    //           Erosion is specified as a number of erosion iterations.
    //           Erosion has less chance of bleeding and changing the zone
    //           for a complete region.
    //           A negative value implements 'growing' the cellZones which
    //           might help with small non-physical gaps inbetween cellZones.
    //           (currently only a single layer growth i.e. -1 is supported)
    //           Default value is 0.
    //nCellZoneErodeIter 2;

    // Optional: delete any region smaller than below fraction of the overall
    //           size (on a per-zone basis). This is occasionally useful
    //           when generating meshes with faceZones as baffles or boundary
    //           faces.
    //minCellFraction 0.001;
    // Optional: same but in absolute number of cells. Default is 0.
    //nMinCells 100;

    // Optional: enable automatic leak closure (default is exit immediately)
    //useLeakClosure true;
}

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

    // Optional: number of smoothing iterations for internal points on
    // refinement interfaces. This will reduce non-orthogonality on
    // refinement interfaces.
    //nSmoothInternal $nSmoothPatch;

    // Maximum relative distance for points to be attracted by surface.
    // True distance is this factor times local maximum edge length.
    tolerance 2.0;

    // Number of mesh displacement relaxation iterations.
    nSolveIter 30;

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

    // (wip) disable snapping to opposite near surfaces (revert to 22x
    //  behaviour)
    // detectNearSurfacesSnap false;


    // 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 false;

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

        // Detect features between multiple surfaces
        // (only for explicitFeatureSnap, default = false)
        multiRegionFeatureSnap false;


        //- When to run face splitting (never at first iteration, always
        //  at last iteration). Is interval. Default -1 (disabled)
        //nFaceSplitInterval 5;


        // (wip) Optional for explicit feature snapping:
        //- Detect baffle edges. Default is true.
        //detectBaffles false;
        //- On any faces where points are on multiple regions (see
        //  multiRegionFeatureSnap) have the other points follow these points
        //  instead of having their own independent movement, i.e. have snapping
        //  to multi-region edges/points take priority. This might aid snapping
        //  to sharp edges that are also region edges. The default is false
        //  since it might also introduce problems - at morphing the patching
        //  might still be wrong so points get 'released' instead of behaving
        //  as any other point.
        //releasePoints true;
        //- Walk along feature edges, adding missing ones. Default is true.
        //stringFeatures false;
        //- If diagonal attraction also attract other face points. Default is
        //  false
        //avoidDiagonal true;
        //- When splitting what concave faces to leave intact. Default is 45
        //  degrees.
        //concaveAngle 30;
        //- When splitting the minimum area ratio of faces. If face split
        //  causes ratio of area less than this do not split. Default is 0.3
        //minAreaRatio 0.3;
        //- Attract points only to the surface they originate from. Default
        //  false. This can improve snapping of intersecting surfaces.
        //  strictRegionSnap true;


    // Choice of mesh motion algorithm to inflate layers (only used for mode
    // castellatedBufferLayer)

        //solver  displacementPointSmoothing;
        //displacementPointSmoothingCoeffs
        //{
        //    // Use laplacian to untangle problem areas
        //    pointSmoother           laplacian;
        //    nPointSmootherIter      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;

    // Layer thickness specification. This can be specified either through the
    // 'thicknessModel' parameter (new) or by specifying the individual
    // settings. The parameters are the cell height of the cells next to the
    // wall ('firstLayerThickness'), the cell height of the cells next to the
    // bulk ('finalLayerThickness'), the expansionRatio ('expansionRatio') and
    // the overall thickness of all layers ('thickness').

    //- specification of firstLayerThickness and overallThicknes. From these
    //  it calculates the needed expansionRatio.
    // thicknessModel firstAndOverall;

    //- specification of firstLayerThickness and expansionRatio.
    // thicknessModel firstAndExpansion;

    //- specification of finalLayerThickness and expansionRatio.
    // thicknessModel finalAndExpansion;

    //- specification of thickness and expansionRatio.
    // thicknessModel overallAndExpansion;

    //- specification of firstLayerThickness and finalLayerThickness. The
    //  firstLayerThickness is always absolute, the finalLayerThickness is
    //  always relative, independent of the relativeSizes setting
    // thicknessModel firstAndRelativeFinal;


        // Expansion factor for layer mesh
        expansionRatio 1.0;

        // Wanted thickness of the layer furthest away from the wall.
        // If relativeSizes this is relative to undistorted size of cell
        // outside layer.
        finalLayerThickness 0.3;


    // Minimum overall thickness of total layers. If for any reason layer
    // cannot be above minThickness do not add layer.
    // If relativeSizes this is relative to undistorted size of cell
    // outside layer..
    minThickness 0.1;


    // Per final patch or faceZone (so not geometry!) the layer information:
    // - whether to use relative or absolute sizes
    // - thicknessModel (or individual settings)
    // - minimum thickness
    //
    // Note: mesh shrinking behaviour changed after 21x. Any non-mentioned
    //       patches now slide unless:
    //          - nSurfaceLayers is explicitly mentioned to be 0.
    //          - angle to nearest surface < slipFeatureAngle (see below)
    layers
    {
        sphere.stl_firstSolid
        {
            nSurfaceLayers 1;

        }
        maxY
        {
            nSurfaceLayers 1;
            // Per patch layer data
            expansionRatio      1.3;
            finalLayerThickness 0.3;
            minThickness        0.1;
        }

        // Disable any mesh shrinking and layer addition on any point of
        // a patch by setting nSurfaceLayers to 0
        frozenPatches
        {
            nSurfaceLayers 0;
        }
    }

    // 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


    // Static analysis of starting mesh

        // When not to extrude surface. 0 is flat surface, 90 is when two faces
        // are perpendicular. Note: was not working correctly < 1806
        featureAngle 120;

        // When to merge patch faces. Default is featureAngle. Useful when
        // featureAngle is large.
        //mergePatchFacesAngle 45;

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


    // Patch displacement

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

        // Smooth layer thickness over surface patches
        nSmoothThickness 10;



    // Choice of mesh shrinking algorithm

        // Optional mesh shrinking algorithm (default is displacementMedialAxis)
        // The displacementMotionSolver is a wrapper around the displacement
        // motion solvers. It needs specification of the solver to use and
        // its control dictionary.
        //meshShrinker displacementMotionSolver;
        //solver displacementLaplacian;
        //displacementLaplacianCoeffs
        //{
        //    diffusivity quadratic inverseDistance
        //    (
        //        sphere.stl_firstSolid
        //        maxY
        //    );
        //}
        // Note that e.g. displacementLaplacian needs entries in
        // fvSchemes, fvSolution. Also specify a minIter > 1 when solving
        // cellDisplacement since otherwise solution might not be sufficiently
        // accurate on points.


    // Medial axis analysis (for use with default displacementMedialAxis)

        // 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;

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

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

        // Optional: limit the number of steps walking away from the surface.
        // Default is unlimited.
        //nMedialAxisIter 10;

        // Optional: smooth displacement after medial axis determination.
        // default is 0.
        //nSmoothDisplacement 90;

        // (wip)Optional: do not extrude any point where
        //   (false) : all surrounding faces are not fully extruded
        //   (true)  : all surrounding points are not extruded
        // Default is false.
        //detectExtrusionIsland true;

        // Optional: do not extrude around sharp edges if both faces are not
        // fully extruded i.e. if one of the faces on either side would
        // become a wedge.
        // Default is 0.5*featureAngle. Set to -180 always attempt extrusion
        //layerTerminationAngle 25;

        // Optional: disable shrinking of edges that have one (or two) points
        // on an extruded patch.
        // Default is false to enable single/two cell thick channels to still
        // have layers. In <=1806 this was true by default. On larger gaps it
        // should have no effect.
        //disableWallEdges true;

        // Optional: at non-patched sides allow mesh to slip if extrusion
        // direction makes angle larger than slipFeatureAngle. Default is
        // 0.5*featureAngle.
        slipFeatureAngle 30;

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


    // Mesh shrinking

        // Create buffer region for new layer terminations, i.e. gradually
        // step down number of layers. Set to <0 to terminate layer in one go.
        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;

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

        // Additional reporting: if there are just a few faces where there
        // are mesh errors (after adding the layers) print their face centres.
        // This helps in tracking down problematic mesh areas.
        //additionalReporting true;
}

// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
    // Specify mesh quality constraints in separate dictionary so can
    // be reused (e.g. checkMesh -meshQuality)
    #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 75;
    }


    // Advanced

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

// Advanced

//// Debug flags
//debugFlags
//(
//    mesh            // write intermediate meshes
//    intersections   // write current mesh intersections as .obj files
//    featureSeeds    // write information about explicit feature edge
//                    // refinement
//    attraction      // write attraction as .obj files
//    layerInfo       // write information about layers
//);
//
//// Write flags
//writeFlags
//(
//    scalarLevels    // write volScalarField with cellLevel for postprocessing
//    layerSets       // write cellSets, faceSets of faces in layer
//    layerFields     // write volScalarField for layer coverage
//);


//// Format for writing lines. E.g. leak path. Default is vtk format.
//setFormat ensight;

//// Format to use for surfaces. E.g. leak-closure faces. Default is vtk format.
//surfaceFormat vtk;

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

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