/*---------------------------------------------------------------------------*\
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    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
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    Copyright (C) 2011-2016 OpenFOAM Foundation
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

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    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
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Class
    Foam::linearUpwind

Group
    grpFvSurfaceInterpolationSchemes

Description
    linearUpwind interpolation scheme class derived from upwind and returns
    upwind weighting factors and also applies a gradient-based explicit
    correction.

SourceFiles
    linearUpwind.C

\*---------------------------------------------------------------------------*/

#ifndef linearUpwind_H
#define linearUpwind_H

#include "upwind.H"
#include "gaussGrad.H"

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

namespace Foam
{

/*---------------------------------------------------------------------------*\
                           Class linearUpwind Declaration
\*---------------------------------------------------------------------------*/

template<class Type>
class linearUpwind
:
    public upwind<Type>
{
    // Private Data

        word gradSchemeName_;


    // Private Member Functions

        //- No copy construct
        linearUpwind(const linearUpwind&) = delete;

        //- No copy assignment
        void operator=(const linearUpwind&) = delete;


public:

    //- Runtime type information
    TypeName("linearUpwind");


    // Constructors

        //- Construct from faceFlux
        linearUpwind
        (
            const fvMesh& mesh,
            const surfaceScalarField& faceFlux
        )
        :
            upwind<Type>(mesh, faceFlux),
            gradSchemeName_("grad")
        {}

        //- Construct from Istream.
        //  The name of the flux field is read from the Istream and looked-up
        //  from the mesh objectRegistry
        linearUpwind
        (
            const fvMesh& mesh,
            Istream& schemeData
        )
        :
            upwind<Type>(mesh, schemeData),
            gradSchemeName_(schemeData)
        {}

        //- Construct from faceFlux and Istream
        linearUpwind
        (
            const fvMesh& mesh,
            const surfaceScalarField& faceFlux,
            Istream& schemeData
        )
        :
            upwind<Type>(mesh, faceFlux, schemeData),
            gradSchemeName_(schemeData)
        {}


    // Member Functions

        //- Return true if this scheme uses an explicit correction
        virtual bool corrected() const
        {
            return true;
        }

        //- Return the explicit correction to the face-interpolate
        virtual tmp<GeometricField<Type, fvsPatchField, surfaceMesh>>
        correction
        (
            const GeometricField<Type, fvPatchField, volMesh>&
        ) const;
};


// Specialize for volVectorField to support cached gradients
template<>
tmp<surfaceVectorField> linearUpwind<vector>::correction
(
    const volVectorField& vf
) const;


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

} // End namespace Foam

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

#endif

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