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[snappyHexMesh] Strange striated surface mesh

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Old   October 9, 2019, 08:44
Default Strange striated surface mesh
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Andrew
Join Date: Mar 2018
Posts: 75
Rep Power: 3
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Hi guys i'm facing with a strage problem in the surface mesh done in snappyhex mesh.
It is something related to the way in which snappy cuts the cells during the snap process, it is clearly seen in the following two screenshots.
I link also the snappyHexMesh dictionary.

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  5                                     |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

    castellatedMesh false;
    snap false;
    addLayers true;
     geometry
    {
        test964.stl
        {
            type triSurfaceMesh;
            name test964;
            appendRegionName false;
        }

        RuotaAnt.stl
        {
            type triSurfaceMesh;
            name RuotaAnt;
            appendRegionName false;
        }

        RuotaPost.stl
        {
            type triSurfaceMesh;
            name RuotaPost;
            appendRegionName false;
        }

        box
        {
            type searchableBox;
            min ( -4.0 -2.0 -2.0 );
            max ( 4.0 2.0 2.0 );
        }

        box0
        {
            type searchableBox;
            min ( -2.0 -1.0 -1.0 );
            max ( 2.0 1.0 1.0 );
        }


    }

    castellatedMeshControls
    {
        features
        (
        
        {
            file "test964.eMesh";
            levels ((0.005 6)); // 0.05
            refineFeatureEdgesOnly false;
        }

        {
            file "RuotaPost.eMesh";
            levels ((0.005 5));
            refineFeatureEdgesOnly false;
        }

        {
            file "RuotaAnt.eMesh";
            levels ((0.005 5));
            refineFeatureEdgesOnly false;
        }
       
        );

        refinementSurfaces
        {
            test964
            {
                level ( 6 6 );
            }
            
            RuotaAnt
            {
                level ( 5 5 );
            }

            RuotaPost
            {
                level ( 5 5 );
            }

        }

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

            box0
            {
                mode inside;
                levels (( 1E5 3 ));
            }
        }

        locationInMesh ( 5.2159 2.2686 2.2052 );
        maxLocalCells 10000000;
        maxGlobalCells 10000000;
        minRefinementCells 0;
        nCellsBetweenLevels 6;
        resolveFeatureAngle 30.0;
        allowFreeStandingZoneFaces true;
        planarAngle 30.0;
        maxLoadUnbalance 0.1;
    }

    snapControls
    {
        nSolveIter 700;
        nSmoothPatch 5;
        tolerance 5;
        nRelaxIter 8;
        nFeatureSnapIter 10;
        implicitFeatureSnap false;
        explicitFeatureSnap true;
        multiRegionFeatureSnap false;
    }

    addLayersControls

{
        layers
        {
            test964
            {
                nSurfaceLayers 1;
            }

            RuotaAnt
            {
                nSurfaceLayers 1;
            }
            
            RuotaPost
            {
                nSurfaceLayers 1;
            }

        }

        relativeSizes false;
        expansionRatio 1;
        finalLayerThickness 0.002;	;
        minThickness 1.0E-9;
        nGrow 0;
        featureAngle 300.0;
        slipFeatureAngle 150.0; // 30
        nRelaxIter 5;
        nSmoothSurfaceNormals 1;
        nSmoothNormals 3;
        nSmoothThickness 20;
        maxFaceThicknessRatio 0.5;
        maxThicknessToMedialRatio 0.3;
        minMedialAxisAngle 90;
        nBufferCellsNoExtrude 0;
        nLayerIter 60;
        nRelaxedIter 20;
        writeVTK false;
        noErrors false;
        layerRecovery 1;
        growZoneLayers false;
        projectGrownUp 0.0;
    }



    meshQualityControls
    {
        maxNonOrtho 65.0;
        maxBoundarySkewness 20;
        maxInternalSkewness 4;
        maxConcave 80.0;
        minFlatness 0.5;
        minVol 1.0E-13;
        minTetQuality 1.0E-15;
        minArea -1.0;
        minTwist 0.02;
        minDeterminant 0.001;
        minFaceWeight 0.05;
        minVolRatio 0.01;
        minTriangleTwist -1.0;
        nSmoothScale 4;
        errorReduction 0.75;
        relaxed
        {
            maxNonOrtho 75;
        }

    }

debugFlags
(

);
writeFlags
(
      scalarLevels
      layerSets
      layerFields
);

mergeTolerance 1e-6;

// ************************************************************************* //
How could i get rid off this problem? what's wrong in your opinion?

thanks you very much for the time spent in this thread, any suggestion is welcomed.

Astan
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