[Pappy]

I am having difficulty figuring out the correct settings for snappyhexmesh to get a well defined and fit mesh to the interface between the symmetry plane and the stl model.

The symmetry plane is created by the initial blockmesh command and the stl file interfaces with this block. Below are pictures of that interface and it is becoming very stagey and jagged. The rest of the mesh(internal mesh on the model) fits quite well.

The featureextract tooL doesn't really help me here because the problem edge is not created until snappyhexmesh fills and fits the domain.

/*--------------------------------*- C++ -*----------------------------------*\
|       o          |                                                          |
|    o     o       | HELYX-OS                                                  |
|   o   O   o      | Version: v2.0.1                                           |
|    o     o       | Web:     http://www.engys.com                            |
|       o          |                                                          |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version 2.0;
    format ascii;
    class dictionary;
    location system;
    object snappyHexMeshDict;
}

    castellatedMesh true;
    snap true;
    addLayers true;
    geometry
    {
        RA3stlrepaired.stl
        {
            type triSurfaceMesh;
            name RA3stlrepaired;
        }

        box
        {
            type searchableBox;
            min ( -400.0 900.0 1700.0 );
            max ( 3800.0 1600.0 8000.0 );
        }

        box0
        {
            type searchableBox;
            min ( 3400.0 0.0 800.0 );
            max ( 3813.0 900.0 4000.0 );
        }

        box1
        {
            type searchableBox;
            min ( 2200.0 0.0 2500.0 );
            max ( 3400.0 900.0 5000.0 );
        }

        box2
        {
            type searchableBox;
            min ( 3500.0 1600.0 5000.0 );
            max ( 3813.0 2800.0 8000.0 );
        }

    }

    castellatedMeshControls
    {
        features
        (
        );
        refinementSurfaces
        {
            RA3stlrepaired
            {
                regions
                {
                    patch
                    {
                        level ( 3 6 );
                    }

                }

                level ( 0 0 );
            }

        }

        refinementRegions
        {
            box
            {
                mode inside;
                levels (( 1E5 2 ));
            }

            box0
            {
                mode inside;
                levels (( 1E5 2 ));
            }

            box1
            {
                mode inside;
                levels (( 1E5 2 ));
            }

            box2
            {
                mode inside;
                levels (( 1E5 2 ));
            }

        }

        locationInMesh ( 0 0 0);
        maxLocalCells 1000000;
        maxGlobalCells 2000000;
        minRefinementCells 10;
        nCellsBetweenLevels 2;
        resolveFeatureAngle 45.0;
        allowFreeStandingZoneFaces false;
    }

    snapControls
    {
        nSolveIter 300;
        nSmoothPatch 3;
        tolerance 10.0;
        nRelaxIter 5;
        nFeatureSnapIter 15;
        implicitFeatureSnap false;
        explicitFeatureSnap true;
        multiRegionFeatureSnap false;
    }

    addLayersControls
    {
        layers
        {
            RA3stlrepaired_patch
            {
                nSurfaceLayers 0;
            }

        }

        relativeSizes true;
        expansionRatio 1.15;
        finalLayerThickness 0.3;
        minThickness 0.01;
        nGrow 0;
        featureAngle 180;
        slipFeatureAngle 30;
        nRelaxIter 3;
        nSmoothSurfaceNormals 1;
        nSmoothNormals 3;
        nSmoothThickness 10;
        maxFaceThicknessRatio 0.7;
        maxThicknessToMedialRatio 0.3;
        minMedianAxisAngle 90;
        nBufferCellsNoExtrude 0;
        nLayerIter 50;
        nRelaxedIter 20;
        minMedialAxisAngle 80;
    }

    meshQualityControls
    {
        maxNonOrtho 65;
        maxBoundarySkewness 20;
        maxInternalSkewness 4;
        maxConcave 90;
        minFlatness 0.5;
        minVol 1.0E-13;
        minTetQuality -1.0E30;
        minArea -1.0;
        minTwist 0.02;
        minDeterminant 0.001;
        minFaceWeight 0.02;
        minVolRatio 0.01;
        minTriangleTwist -1.0;
        nSmoothScale 4;
        errorReduction 0.75;
    }

    debug 0;
    mergeTolerance 1.0E-6;

The third picture is an internal cut away within the mesh, there you can see that snappyhexmesh has match the surface pretty good. The only issue is on the edge of the mesh domain(where the symmetry plane is located).

Thanks