[B_SZ]

Hello everyone,

I am a beginner with OpenFOAM and CFD in general , I have been working one for more than a month on it and I still have a lot to learn.
For my project , I need to modelize a 3D wing and use ChtMultiRegionFOAM .
For 2 weeks, I have been struggling with the meshing using snappyHexMesh and I don't get a good mesh ( Failed check Mesh) and the quality of the solid is pretty bad.
I think it might be due to refinement lvl but nor really sure , as well my case is pretty heavy.

Here is the snappy hex mesh file and my folder case :

https://drive.google.com/drive/folde...Ex83MDyv02WYox

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

#includeEtc "caseDicts/mesh/generation/snappyHexMeshDict.cfg"

castellatedMesh on;
snap on;
addLayers on;

geometry
{
wing
{
type triSurfaceMesh;
file "Airfoilrefined.stl";
}

refinementBox
{
type searchableBox;
min (-0.15 -0.5 -1);
max (6.85 0.5 1);

}
};

castellatedMeshControls
{
maxLocalCells 100000;

maxGlobalCells 2000000;

minRefinementCells 100;

nCellsBetweenLevels 10;

refinementSurfaces
{
wing
{
level ( 4 8 );
}
}

resolveFeatureAngle 30;

refinementRegions
{
refinementBox
{
mode inside;
levels ( ( 2 7 ) );
}
}

locationInMesh ( 3 0 11);


allowFreeStandingZoneFaces true;
}

snapControls
{
// Number of patch smoothing iterations before finding correspondence
// to surface
nSmoothPatch 3;

// Maximum relative distance for points to be attracted by surface.
// True distance is this factor times local maximum edge length.
// Note: changed(corrected) w.r.t 17x! (17x used 2* tolerance)
tolerance 3.0;

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

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

// Feature snapping

// Number of feature edge snapping iterations.
// Leave out altogether to disable.
nFeatureSnapIter 15;

// 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;
}

// 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
{
wing
{
nSurfaceLayers 2;
}
}

// Expansion factor for layer mesh
expansionRatio 1.3;

// 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 1;

// 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.
// See relativeSizes parameter.
minThickness 0.5;

// 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
// are perpendicular
featureAngle 60;

// 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 16x! 90 degrees corresponds to 130 in 16x.
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 20;
maxInternalSkewness 4;

//- 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-13;

//- Minimum quality of the tet formed by the face-centre
// and variable base point minimum decomposition triangles and
// the cell centre. 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 0.05;

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

//- minFaceWeight (0 -> 0.5)
minFaceWeight 0.05;

//- 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

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

Thank you for your help!