[Krao]

Hi dear cfMesh/foam users,

I am using cfMesh since last two years for my cfd applications, thanks to the great tool. So far I had very good experience with cfMesh. As of now I am generating mesh for a wing of propeller which has a similar airfoil profile throughout as shown in the figure airfoil.png. Due to very thin region near the trailing edge no matter how good my refinements are I am unable to generate a mesh with more than two boundary layers. Also with two BLs I am still having a saw-tooth shaped airfoil profile at the trailing edge. Any attempt to add more boundary layers or making more refinements in the region resulting in poor to worst mesh quality during the checkMesh. It would be very great if anyone using cfMesh share their experience for a similar application/similar problem.

My meshing procedure is as follows,

1) Generate geometry in CAD (.stl)
2) Clean/Simplify the geometry using blender(de-featuring)
3) Generate the bounding box
4) Extract/generate surfaces for surfaceRefinement
5) Extract features using surfaceFeatureEdges and storing it as .vtk which is used for edge refinement
6) cartesianMesh to generate mesh

My meshDict,

surfaceFile "dynamic.stl";

maxCellSize 0.027;

localRefinement
{


blade
{
additionalRefinementLevels 4;
refinementThickness 0.03;
//cellSize 0.05;
}

}


objectRefinements
{

cylindrical1
{
type cone;
p0 (0 0 0.06);
p1 (0 0 -0.06);
radius0 0.225;
radius1 0.225;
additionalRefinementLevels 2;
refinementThickness 0.027;
}
box1
{
type box;
lengthX 0.22;
lengthY 0.08;
lengthZ 0.045;
centre (-0.12 0.016 -0.011);
additionalRefinementLevels 4;
refinementThickness 0.00375;
}

}
edgeMeshRefinement
{
edge1
{
edgeFile "edgemesh_featureEdges.vtk"; //tip
additionalRefinementLevels 7;
//cellSize 0.005;
refinementThickness 0.0002;
}
}

surfaceMeshRefinement
{
SR1 //tip
{

surfaceFile "SR1.stl";
additionalRefinementLevels 7;
refinementThickness 0.0009;

}



SR2 //LE
{

surfaceFile "SR2.stl";
additionalRefinementLevels 7;
refinementThickness 0.0009;

}

SR3 //TE
{

surfaceFile "SR3.stl";
additionalRefinementLevels 7;
refinementThickness 0.0009;

}


}

boundaryLayers
{


patchBoundaryLayers
{

"(blade)" //patch name
{
nLayers 2;
thicknessRatio 1.2;
maxFirstLayerThickness 0.001;
allowDiscontinuity 0;

}



}

optimiseLayer 1;

optimisationParameters
{

nSmoothNormals 5;

maxNumIterations 5;

// feature size factor. Reasonable range <0.2, 0.5>
// lower values force thinner layers
featureSizeFactor 0.4;

// shall the normal vectors be recalculated
reCalculateNormals 1;

// relative thickess variation between two hair nSmoothNormals
// lower value produce thinner and more uniform layers
relThicknessTol 0.1;
}

}




renameBoundary
{

newPatchNames
{

"blade"
{
newName blade;
type wall;
}

"(patch0|patch1|patch2)"
{
newName rotor;
type patch;
}

}



}

Thank you in advance
Krao