Edge meshing is important part of meshing using snappyHexMesh. Edge meshing feature helps a lot to eliminate problems with catching sharp edges of objects or in determining intersections between boundaries. Utility surfaceFeatureExtract can extract sharp edges from .STL surfaces.

This utility reads settings from its dictionary file surfaceFeatureExtractDict located in system subdirectory.

Let us view content of an example surfaceFeatureExtractDict extracting sharp edges from file t-housing.stl:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.2                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      surfaceFeatureExtractDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

t-housing.stl
{
    extractionMethod    extractFromSurface;

    extractFromSurfaceCoeffs
    {
        includedAngle   100;
    }

    writeObj                yes;
}

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

It extracts edge features and saves it to a new file t-housing.eMesh located in the constant/triSurface subdirectory. Parameter includedAngle specifies an angle in degrees. Edges having lower angle between its faces are written down. Parameter writeObj set to yes means the output will also be written in the .obj format to the constant/extendedFeatureEdgeMesh subdirectory. This format can be viewed directly in paraview. To run the utility, use following command:
 surfaceFeatureExtract