[postechkian]

Hello..! I'm beginner of snappyHexMesh.
I'm making some furnace grids with SHM, but it can't make well....

below is my snappyHexMeshDict
and I also attach images about this problem!



/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.1 |
| \\ / 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; // make basic mesh?
snap true; // decide to snap back to surface?
addLayers true; // decide to add viscous layers?


geometry // Load in STL files here
{
cylinder.stl {type triSurfaceMesh; name cylinder;}
inlet.stl {type triSurfaceMesh; name inlet;}
outlet.stl {type triSurfaceMesh; name outlet;}
body.stl {type triSurfaceMesh; name body;}
bottom.stl {type triSurfaceMesh; name bottom;}
head.stl {type triSurfaceMesh; name head;}
wall.stl {type triSurfaceMesh; name wall;}
//refineHole {type searchableBox; min (5 5 5); max (10 10 10);}
};

castellatedMeshControls
{

maxLocalCells 1000000000;
maxGlobalCells 2000000000;
minRefinementCells 10;
nCellsBetweenLevels 3;
maxLoadUnbalance 0.10;


features // taken from STL from each .eMesh file created by "SurfaceFeatureExtract" command
(
{file "inlet.eMesh"; level 5;}
{file "outlet.eMesh"; level 5;}
{file "body.eMesh"; level 5;}
{file "bottom.eMesh"; level 5;}
{file "head.eMesh"; level 6;}
{file "wall.eMesh"; level 6;}
);



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

refinementSurfaces // surface wise min and max refinement level
{
inlet{level (0 0);}
outlet{level (0 0);}
wall{level (6 6);}
body{level (4 4);}
bottom{level (4 4);}
head{level (6 6);}

}


resolveFeatureAngle 80; // Resolve sharp angles // Default 30

refinementRegions // In descending levels of fine-ness
{cylinder {mode distance; levels ((0.0006 4) (0.002 3) (0.01 2));}}
locationInMesh (0 2 0); // to decide which side of mesh to keep **
allowFreeStandingZoneFaces true;
}



// Settings for the snapping.
snapControls
{
//- Number of patch smoothing iterations before finding correspondence
// to surface
nSmoothPatch 5;

//- 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 30;

//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 7;

// Feature snapping

//- Number of feature edge snapping iterations.
// Leave out altogether to disable.
nFeatureSnapIter 15; // defalut is 10
implicitFeatureSnap false; // default is false - detects without doing surfacFeatureExtract
explicitFeatureSnap true; // default is true
multiRegionFeatureSnap false; // default is false - detects features between multiple surfaces

// When to run face splitting (never at first iteration, always at last iteration)
// Is interaval. Default -1 (disabled)
// Recommendation : set to half the number of feature snap iterations
nFaceSplitInterval 5;
}


// Settings for the layer addition.
addLayersControls // add the PATCH names from inside the STL file so STLpatchName_insideSTLName
{
relativeSizes false;

layers
{
body {nSurfaceLayers 5;}
head {nSurfaceLayers 5;}
bottom {nSurfaceLayers 5;}
wall {nSurfaceLayers 5;}
}

expansionRatio 1.3;
finalLayerThickness 0.00048;
minThickness 0.00024;
nGrow 0;


// Advanced settings
featureAngle 80; //- when not to extrude surface. 0 is flat, 90 is right angle.
nRelaxIter 3; //- Max# of snapping relaxation iter. Should stop before upon reaching a correct mesh.
nSmoothSurfaceNormals 1;// Number of smoothing iterations of surface normals
nSmoothNormals 3; // Number of smoothing iterations of interior mesh movement direction
nSmoothThickness 10; // Smooth layer thickness over surface patches
maxFaceThicknessRatio 0.5; // Stop layer growth on highly warped cells
maxThicknessToMedialRatio 0.3; // Reduce layer growth where ratio thickness to medial distance is large
minMedianAxisAngle 130; // Angle used to pick up medial axis points
nBufferCellsNoExtrude 0; // Create buffer region for new layer terminations
nLayerIter 50; // Overall max number of layer addition iterations

// Do not extrude around sharp edge if not both faces are extruded.
// Defalut is 0.5*featureAngle. Set to -180 always attempt extrusion
layerTerminationAngle -180;

// 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;
}




// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
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 75;
}

// Advanced

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


// Advanced

// Write flags
writeFlags
(
scalarLevels // write volScalarField with cellLevel for postprocessing
layerSets // write cellSets, faceSets of faces in layer
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;


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