[rocketLauncher]

Hello all,

Very new to snappyHexMesh, but I have been following some tutorials (Wolf Dynamics etc). During the castellation step, instead of the blockmesh domain 'sticking' to my geometry, it's like the geometry is substracted from the domain. Any ideas as to what's going wrong?

I have attached a picture and the snappyHexMeshDict. Let me know if you need more info

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.0                                 |
|   \\  /    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 true;
snap            false;
addLayers       false;

// Geometry. Definition of all surfaces. All surfaces are of class
// searchableSurface.
// Surfaces are used
// - to specify refinement for any mesh cell intersecting it
// - to specify refinement for any mesh cell inside/outside/near
// - to 'snap' the mesh boundary to the surface
geometry
{
    elbowSnappyGeo.stl
    {
        type    triSurfaceMesh;
        name    elbow;
        regions
        {
            inlet1 
            {
                name inlet1;
            }
            inlet2 
            {
                name inlet2;
            }
            outlet 
            {
                name outlet;
            }
            walls    
            {
                name walls;
            }
            symmetry_plane    
            {
                name symmetry_plane;
            }
        }
    }
}

// Settings for the castellatedMesh generation.
castellatedMeshControls
{
    // Refinement parameters
    // ~~~~~~~~~~~~~~~~~~~~~

    maxLocalCells 50000;
    maxGlobalCells 1000000;
    minRefinementCells 0;
    maxLoadUnbalance 0.10;
    nCellsBetweenLevels 1;

    // Explicit feature edge refinement
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    features
    (
	
        /*{
            file    "elbowSnappyGeo.eMesh";
            level   4;
        }*/
    );

    // Surface based refinement
    // ~~~~~~~~~~~~~~~~~~~~~~~~
    refinementSurfaces
    {
        elbow
        {
            level (4 4); // default 
            
            regions
            {
                inlet1
                {   
                    level (4 4);
                    patchInfo
                    {
                        type patch;
                    }
                }

                inlet2
                {
                    level (4 4);
                    patchInfo
                    {
                        type patch;
                    }
                }
                outlet
                {
                    level (4 4);
                    patchInfo
                    {
                        type patch;
                    }
                }
                symmetry_plane
                {
                    level (4 4);
                    patchInfo
                    {
                        type symmetry;
                    }
                }
                walls
                {
                    level (4 4);
                    patchInfo
                    {
                        type wall;
                    }
                 }
             }
        }
    }

    // Resolve sharp angles
    resolveFeatureAngle 30;

    // Region-wise refinement
    // ~~~~~~~~~~~~~~~~~~~~~~
    refinementRegions
    {
        // Define any refinement regions here if needed
	/*elbow
	{

		mode distance;
		levels ((1e2 2));
	}*/
	
    };

    // Mesh selection
    // ~~~~~~~~~~~~~~
    locationInMesh (-0.0429496835859303 0.00771134940190549 -0.0425954894548383);
    allowFreeStandingZoneFaces true;
}

// Settings for the snapping.
snapControls
{
    nSmoothPatch 3;
    tolerance 2.0;
    nSolveIter 30;
    nRelaxIter 5;

    // Feature snapping
    nFeatureSnapIter 10;
    implicitFeatureSnap false;
    explicitFeatureSnap true;
    multiRegionFeatureSnap true;
}

// Settings for the layer addition.
addLayersControls
{
    relativeSizes true;

    layers
    {
        walls
        {
            nSurfaceLayers 6;
        }
    }

    expansionRatio 1.2;
    finalLayerThickness 0.008;
    minThickness 0.001;
    nGrow 0;
    featureAngle 5;
    slipFeatureAngle 30;
    nRelaxIter 3;
    nSmoothSurfaceNormals 1;
    nSmoothNormals 3;
    nSmoothThickness 10;
    maxFaceThicknessRatio 0.5;
    maxThicknessToMedialRatio 0.3;
    minMedialAxisAngle 90;
    nBufferCellsNoExtrude 0;
    nLayerIter 50;
}

// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
    maxNonOrtho 65;
    maxBoundarySkewness 20;
    maxInternalSkewness 4;
    maxConcave 80;
    minVol 1e-13;
    minTetQuality 1e-30;
    minArea -1;
    minTwist 0.02;
    minDeterminant 0.001;
    minFaceWeight 0.02;
    minVolRatio 0.01;
    minTriangleTwist -1;

    // Advanced
    nSmoothScale 4;
    errorReduction 0.75;
}

// Advanced

// Flags for optional output
debug 0;

// Merge tolerance. Is fraction of overall bounding box of initial mesh.
mergeTolerance 1e-6;

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

[Yann]

Hello,

Most probably this:

locationInMesh (-0.0429496835859303 0.00771134940190549 -0.0425954894548383);

Where is this point located?
If you intend to mesh the inside of the pipe, this point should be inside it too. (you can check in ParaView to make sure there is no mistake. For instance, scaling issue)

Yann