CFD Online Discussion Forums - [snappyHexMesh] SHM addLayers doesnt work on the small surface

Hello,

I just tried to make a simple mesh on a car geometry with snappyHexMesh.
everything worked quite well except addlayer. actually addlayer, add layers on all surface except small ones. I changed various paramters but did not answer,how can i fix this?

Here is my SHMDict:

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;

}

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



// Which of the steps to run

castellatedMesh false;

snap            false;

addLayers       true;





geometry

{

    //main {type triSurfaceMesh;file "main.obj";}

    left {type triSurfaceMesh;file "left.obj";}

    right {type triSurfaceMesh;file "right.obj";}

    roof {type triSurfaceMesh;file "roof.obj";}

    fhood {type triSurfaceMesh;file "fhood.obj";}

    rhood {type triSurfaceMesh;file "rhood.obj";}

    fbumper {type triSurfaceMesh;file "fbumper.obj";}

    rbumper {type triSurfaceMesh;file "rbumper.obj";}

    floor {type triSurfaceMesh;file "floor.obj";}

    tire {type triSurfaceMesh;file "tire.obj";}

    refinementBox {type searchableBox;min (-1000 0 -1000);max (5000 1000 1000);}

    refinementCylinder {type searchableCylinder;point1 (-1000 500 -1000);point2 (-1000 500 1000);radius 500;}

    

};

castellatedMeshControls

{



    maxLocalCells 100000; //max cell per cpu core

    maxGlobalCells 2000000; //max cells to use before mesh deletion step

    minRefinementCells 10; //zero means no bad cell are allowed during refinement stage

    maxLoadUnbalance 0.10;

    nCellsBetweenLevels 7; //expension factor between each high & low refinement zone

    

    features //taken from stl from each .emesh file created by "surfaceFeatureExtract" command

    (

        //{file "main.eMesh";level 3;}

    {file "left.eMesh";level 5;}

    {file "right.eMesh";level 5;}

    {file "roof.eMesh";level 5;}

    {file "fhood.eMesh";level 5;}

    {file "rhood.eMesh";level 5;}

    {file "fbumper.eMesh";level 5;}

    {file "rbumper.eMesh";level 5;}

    {file "floor.eMesh";level 5;}

    {file "tire.eMesh";level 5;}

    );

    refinementSurfaces

    {

    //main {level (3 3);patchInfo {type wall;inGroups (sedanGroup);}}        

    left {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    right {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    roof {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    fhood {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    rhood {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    fbumper {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    rbumper {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    floor {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    tire {level (5 5);patchInfo {type wall;inGroups (sedanGroup);}}

    }



    // Resolve sharp angles

    resolveFeatureAngle 15;





    // Region-wise refinement    

    refinementRegions

    {

        refinementBox {mode inside;levels ((1E15 2));}

    refinementCylinder {mode inside;levels ((1E15 2));}

    }





    // Mesh selection

    // ~~~~~~~~~~~~~~



    // After refinement patches get added for all refinementSurfaces and

    // all cells intersecting the surfaces get put into these patches. The

    // section reachable from the locationInMesh is kept.

    // NOTE: This point should never be on a face, always inside a cell, even

    // after refinement.

    locationInMesh (-500 200 0);//(1000 500 0)





    // Whether any faceZones (as specified in the refinementSurfaces)

    // are only on the boundary of corresponding cellZones or also allow

    // free-standing zone faces. Not used if there are no faceZones.

    allowFreeStandingZoneFaces true;

}







// Settings for the snapping.

snapControls

{

    //- Number of patch smoothing iterations before finding correspondence

    //  to surface

    nSmoothPatch 10;//3



    //- Relative distance for points to be attracted by surface feature point

    //  or edge. True distance is this factor times local

    //  maximum edge length.

    tolerance 3    ;//2



    //- Number of mesh displacement relaxation iterations.

    nSolveIter 100;



    //- Maximum number of snapping relaxation iterations. Should stop

    //  before upon reaching a correct mesh.

    nRelaxIter 5;//5



    // Feature snapping



        //- Number of feature edge snapping iterations.

        //  Leave out altogether to disable.

        nFeatureSnapIter 10;



        //- Detect (geometric only) features by sampling the surface

        //  (default=false).

        implicitFeatureSnap false;



        //- Use castellatedMeshControls::features (default = true)

        explicitFeatureSnap true;



        //- Detect points on multiple surfaces (only for explicitFeatureSnap)

        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 false;



    // Per final patch (so not geometry!) the layer information

    layers

    {

        //"(main).*" {nSurfaceLayers 5;}

    roof {nSurfaceLayers 4;}

    fhood {nSurfaceLayers 4;}

    rhood {nSurfaceLayers 4;}

    fbumper {nSurfaceLayers 4;}

    rbumper {nSurfaceLayers 4;}

    left {nSurfaceLayers 4;}

    right {nSurfaceLayers 4;}

    floor {nSurfaceLayers 4;}

    tire {nSurfaceLayers 4;}

    }



    // Expansion factor for layer mesh

    expansionRatio 1.5;//1.5



    // 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 2.5;//0.3



    // 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.

    minThickness 0.0001;//00.1s



    // 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;//0



    // Advanced settings



    // When not to extrude surface. 0 is flat surface, 90 is when two faces

    // are perpendicular

    featureAngle 160;//150

    //mergePatchFacesAngle 45;

    

    // At non-patched sides allow mesh to slip if extrusion direction makes

    // angle larger than slipFeatureAngle.

    slipFeatureAngle 30;

    

    // Maximum number of snapping relaxation iterations. Should stop

    // before upon reaching a correct mesh.

    nRelaxIter 3;



    // Number of smoothing iterations of surface normals

    nSmoothSurfaceNormals 0;//0



    // Number of smoothing iterations of interior mesh movement direction

    nSmoothNormals 3;//3



    // Smooth layer thickness over surface patches

    nSmoothThickness 10;//10



    // Stop layer growth on highly warped cells

    maxFaceThicknessRatio 0.5;//0.05



    // 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 17x! 90 degrees corresponds to 130 in 17x.

    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 30;//30

}







// Generic mesh quality settings. At any undoable phase these determine

// where to undo.

meshQualityControls

{

    #include "meshQualityDict"



    maxBoundarySkewness 20;

    maxInternalSkewness 6;

    // Advanced



    //- Number of error distribution iterations

    nSmoothScale 4;

    //- Amount to scale back displacement at error points

    errorReduction 0.75;

}





// Advanced



// Write flags

writeFlags

(

    scalarLevels

    layerSets

    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;





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

and blockMeshDict:

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      blockMeshDict;

}



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



convertToMeters 1000;



vertices

(

    (-3 0 -3)

    (9 0 -3)

    (9 3 -3)

    (-3 3 -3)

    (-3 0 3)

    (9 0 3)

    (9 3 3)

    (-3 3 3)

);

blocks

(

    hex (0 1 2 3 4 5 6 7) (48 12 24) simpleGrading (1 1 1)

);



edges

(

);



boundary

(

    frontAndBack

    {

        type patch;

        faces

        (

            (4 5 6 7)

            (3 2 1 0)

        );

    }

    inlet

    {

        type patch;

        faces

        (

            (0 4 7 3)

        );

    }

    outlet

    {

        type patch;

        faces

        (

            (2 6 5 1)

        );

    }

    lowerWall

    {

        type wall;

        faces

        (

            (0 1 5 4)

        );

    }

    upperWall

    {

        type patch;

        faces

        (

            (2 3 7 6)

        );

    }

    

);





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

thanks