Edge meshing is important part of a mesh creation using snappyHexMesh. Edge meshing feature helps a lot to eliminate problems with catching sharp edges of objects or intersections between boundaries. Utility surfaceFeatureExtract can extract sharp edges from any single .STL surface.

As an example of extracting sharp edges from file c-housing.stl a following surfaceFeatureExtractDict file, located in the system directory, is presented:

/*--------------------------------*- 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;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

c-housing.stl
{
    extractionMethod    extractFromSurface;

    extractFromSurfaceCoeffs
    {
        includedAngle   120;
    }

    writeObj                yes;
}

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

Actual extraction is performed by following command

 surfaceFeatureExtract

It extracts edge features and saves it to a new file named c-housing.eMesh located in the constant/triSurface directory. Option -includedAngle specifies the angle in degrees. Edges having lower angle between its faces are written down. Option writeObj set to yes writes the result also to constant/extendedFeatureEdgeMesh/c-housing_edgeMesh.obj. This file can be viewed in paraview directly.