ENH: centralize more libraries in src/phaseSystemModels

- prelude to code refactoring

NOTE
    no source code change in this commit, only relocation,
    renaming and adjustment of Make/{files,options}

src/phaseSystemModels/multiphaseEuler/interfacialModels/dragModels/dragModel/dragModel.H

@@ -0,0 +1,154 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2011-2015 OpenFOAM Foundation
+-------------------------------------------------------------------------------
+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::dragModel
+
+Description
+
+SourceFiles
+    dragModel.C
+    newDragModel.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef dragModel_H
+#define dragModel_H
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "dictionary.H"
+#include "phaseModel.H"
+#include "runTimeSelectionTables.H"
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                           Class dragModel Declaration
+\*---------------------------------------------------------------------------*/
+
+class dragModel
+{
+protected:
+
+    // Protected data
+
+        const dictionary& interfaceDict_;
+        const phaseModel& phase1_;
+        const phaseModel& phase2_;
+        dimensionedScalar residualPhaseFraction_;
+        dimensionedScalar residualSlip_;
+
+public:
+
+    //- Runtime type information
+    TypeName("dragModel");
+
+
+    // Declare runtime construction
+
+        declareRunTimeSelectionTable
+        (
+            autoPtr,
+            dragModel,
+            dictionary,
+            (
+                const dictionary& interfaceDict,
+                const phaseModel& phase1,
+                const phaseModel& phase2
+            ),
+            (interfaceDict, phase1, phase2)
+        );
+
+
+    // Constructors
+
+        dragModel
+        (
+            const dictionary& interfaceDict,
+            const phaseModel& phase1,
+            const phaseModel& phase2
+        );
+
+
+    //- Destructor
+    virtual ~dragModel();
+
+
+    // Selectors
+
+        static autoPtr<dragModel> New
+        (
+            const dictionary& interfaceDict,
+            const phaseModel& phase1,
+            const phaseModel& phase2
+        );
+
+
+    // Member Functions
+
+        const phaseModel& phase1() const
+        {
+            return phase1_;
+        }
+
+        const phaseModel& phase2() const
+        {
+            return phase2_;
+        }
+
+        const dimensionedScalar& residualPhaseFraction() const
+        {
+            return residualPhaseFraction_;
+        }
+
+        const dimensionedScalar& residualSlip() const
+        {
+            return residualSlip_;
+        }
+
+        //- The drag function K used in the momentum eq.
+        //    ddt(alpha1*rho1*U1) + ... = ... alpha1*alpha2*K*(U1-U2)
+        //    ddt(alpha2*rho2*U2) + ...  = ... alpha1*alpha2*K*(U2-U1)
+        // ********************************** NB! *****************************
+        // for numerical reasons alpha1 and alpha2 has been
+        // extracted from the dragFunction K,
+        // so you MUST divide K by alpha1*alpha2 when implementing the drag
+        // function
+        // ********************************** NB! *****************************
+        virtual tmp<volScalarField> K(const volScalarField& Ur) const = 0;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //