/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | foam-extend: Open Source CFD
   \\    /   O peration     | Version:     4.0
    \\  /    A nd           | Web:         http://www.foam-extend.org
     \\/     M anipulation  | For copyright notice see file Copyright
-------------------------------------------------------------------------------
License
    This file is part of foam-extend.

    foam-extend 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.

    foam-extend 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 foam-extend.  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 volScalarField& alpha_;
        const phaseModel& phasea_;
        const phaseModel& phaseb_;


public:

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


    // Declare runtime construction

        declareRunTimeSelectionTable
        (
            autoPtr,
            dragModel,
            dictionary,
            (
                const dictionary& interfaceDict,
                const volScalarField& alpha,
                const phaseModel& phasea,
                const phaseModel& phaseb
            ),
            (interfaceDict, alpha, phasea, phaseb)
        );


    // Constructors

        dragModel
        (
            const dictionary& interfaceDict,
            const volScalarField& alpha,
            const phaseModel& phasea,
            const phaseModel& phaseb
        );


    // Destructor

        virtual ~dragModel();


    // Selectors

        static autoPtr<dragModel> New
        (
            const dictionary& interfaceDict,
            const volScalarField& alpha,
            const phaseModel& phasea,
            const phaseModel& phaseb
        );


    // Member Functions

        //- the dragfunction K used in the momentum eq.
        //    ddt(alpha*rhoa*Ua) + ... = ... alpha*beta*K*(Ua-Ub)
        //    ddt(beta*rhob*Ub) + ...  = ... alpha*beta*K*(Ub-Ua)
        // ********************************** NB ! *****************************
        // for numerical reasons alpha and beta has been
        // extracted from the dragFunction K,
        // so you MUST divide K by alpha*beta when implemnting the drag function
        // ********************************** NB ! *****************************
        virtual tmp<volScalarField> K(const volScalarField& Ur) const = 0;
};


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

} // End namespace Foam

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

#endif

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