wallDist: now a MeshObject cached and updated automatically with a run-time selected algorithm

When using models which require the wallDist e.g. kOmegaSST it will
request the method to be used from the wallDist sub-dictionary in
fvSchemes e.g.

wallDist
{
    method meshWave;
}

specifies the mesh-wave method as hard-coded in previous OpenFOAM versions.

src/finiteVolume/fvMesh/wallDist/patchDistMethods/patchDistMethod/patchDistMethod.H

@@ -0,0 +1,152 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2015 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::patchDistMethod
+
+Description
+    Specialisation of patchDist for wall distance calculation
+
+SourceFiles
+    patchDistMethod.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef patchDistMethod_H
+#define patchDistMethod_H
+
+#include "dictionary.H"
+#include "HashSet.H"
+#include "volFieldsFwd.H"
+#include "mapPolyMesh.H"
+#include "runTimeSelectionTables.H"
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+class fvMesh;
+
+/*---------------------------------------------------------------------------*\
+                          Class patchDistMethod Declaration
+\*---------------------------------------------------------------------------*/
+
+class patchDistMethod
+{
+
+protected:
+
+    // Protected Member Data
+
+        //- Reference to the mesh
+        const fvMesh& mesh_;
+
+        //- Set of patch IDs
+        const labelHashSet patchIDs_;
+
+
+private:
+
+    // Private Member Functions
+
+        //- Disallow default bitwise copy construct
+        patchDistMethod(const patchDistMethod&);
+
+        //- Disallow default bitwise assignment
+        void operator=(const patchDistMethod&);
+
+
+public:
+
+    //- Runtime type information
+    TypeName("patchDistMethod");
+
+
+    // Declare runtime construction
+
+        declareRunTimeSelectionTable
+        (
+            autoPtr,
+            patchDistMethod,
+            dictionary,
+            (
+                const dictionary& dict,
+                const fvMesh& mesh,
+                const labelHashSet& patchIDs
+            ),
+            (dict, mesh, patchIDs)
+        );
+
+
+    // Constructors
+
+        //- Construct from mesh and patch ID set
+        patchDistMethod
+        (
+            const fvMesh& mesh,
+            const labelHashSet& patchIDs
+        );
+
+
+    // Selectors
+
+        static autoPtr<patchDistMethod> New
+        (
+            const dictionary& dict,
+            const fvMesh& mesh,
+            const labelHashSet& patchIDs
+        );
+
+
+    //- Destructor
+    virtual ~patchDistMethod();
+
+
+    // Member Functions
+
+        //- Update cached geometry when the mesh moves
+        virtual bool movePoints()
+        {
+            return true;
+        }
+
+        //- Update cached topology and geometry when the mesh changes
+        virtual void updateMesh(const mapPolyMesh&)
+        {}
+
+        //- Correct the given distance-to-patch field
+        virtual bool correct(volScalarField& y) = 0;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //