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Snappyhexmesh Cyclon overset construction
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surfaceFeatureExtract dictionary
==================================

In the constant directory it is created the triSurface subdictionary and then imported the surface files
all.slt, porous1.stl and porous2.stl.

From the all directory run:

.. code-block:: bash

    > surfaceFeatureExtract >> logFile

It produces the files:

- all.eMesh
- porous1.eMesh
- porous2.eMesh

and:

The new folder extendedFeatureEdgeMesh with the files:

- all.extendedFeatureEdgeMesh
- porous1.extendedFeatureEdgeMesh
- porous2.extendedFeatureEdgeMesh



Extracts and writes surface features to file. All but the basic feature extraction is a work-in-progress. 

Original source file surfaceFeatureExtract.C

The extraction process is driven by the system/surfaceFeatureExtractDict dictionary, but the -dict option
 can be used to define an alternative location. The system/surfaceFeatureExtractDict dictionary contains 
 entries for each extraction process. The name of the individual dictionary is used to load the input surface
 (found under constant/triSurface) and also as the basename for the output.

If the surfaces entry is present in a sub-dictionary, it has absolute precedence over a surface name deduced 
from the dictionary name. If the dictionary name itself does not have an extension, the surfaces entry becomes 
mandatory since in this case the dictionary name cannot represent an input surface file (ie, there is no file extension). The surfaces entry is a wordRe list, which allows loading and combining of multiple surfaces. Any exactly specified surface names must exist, but surfaces selected via regular expressions need not exist. The selection mechanism preserves order and is without duplicates.

.. code-block:: bash
		
    /*--------------------------------*- C++ -*----------------------------------*\
    | =========                 |                                                 |
    | \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
    |  \\    /   O peration     | Version:  7.x                                   |
    |   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
    |    \\/     M anipulation  |                                                 |
    \*---------------------------------------------------------------------------*/
    FoamFile
    {
        version     2.0;
        format      ascii;
        class       dictionary;
        object      surfaceFeatureExtractDict;
    }
    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

    all.stl
    {
        // How to obtain raw features (extractFromFile || extractFromSurface)
        extractionMethod    extractFromSurface;

        extractFromSurfaceCoeffs
        {
            // Mark edges whose adjacent surface normals are at an angle less
            // than includedAngle as features
            // - 0  : selects no edges
            // - 180: selects all edges
            includedAngle   150;
        }

        // Write options

            // Write features to obj format for postprocessing
            writeObj                no;
    }

    porous.stl
    {
        // How to obtain raw features (extractFromFile || extractFromSurface)
        extractionMethod    extractFromSurface;

        extractFromSurfaceCoeffs
        {
            // Mark edges whose adjacent surface normals are at an angle less
            // than includedAngle as features
            // - 0  : selects no edges
            // - 180: selects all edges
            includedAngle   150;
        }

        // Write options

            // Write features to obj format for postprocessing
            writeObj                no;
    }
    // ************************************************************************* //