/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 1991-2004 OpenCFD Ltd.
     \\/     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 2 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, write to the Free Software Foundation,
    Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

Class
    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

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