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Class
    Foam::dragModels::AttouFerschneider

Description
    Attou and Ferschneider's Drag model for film flow through packed beds. The
    implementation follows the description of Gunjal and Ranade, who, in the
    reference below, formulate the model in more convenient terms.

    Reference:
    \verbatim
        Gunjal, P. R., & Ranade, V. V. (2007).
        Modeling of laboratory and commercial scale hydro-processing reactors
        using CFD.
        Chemical Engineering Science, 62(18-20), 5512-5526.
    \endverbatim

SourceFiles
    AttouFerschneider.C

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

#ifndef AttouFerschneider_H
#define AttouFerschneider_H

#include "dragModel.H"

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

namespace Foam
{

// Forward Declarations
class phasePair;
class phaseModel;

namespace dragModels
{

/*---------------------------------------------------------------------------*\
                           Class AttouFerschneider Declaration
\*---------------------------------------------------------------------------*/

class AttouFerschneider
:
    public dragModel
{
    // Private Data

        //- Name of the gaseous phase
        const word gasName_;

        //- Name of the liquidphase
        const word liquidName_;

        //- Name of the solid phase
        const word solidName_;

        //- Ergun constant 1
        const dimensionedScalar E1_;

        //- Ergun constant 2
        const dimensionedScalar E2_;


    // Private Member Functions

        //- Return the momentum transfer coefficient between gas and liquid
        virtual tmp<volScalarField> KGasLiquid
        (
            const phaseModel& gas,
            const phaseModel& liquid
        ) const;

        //- Return the momentum transfer coefficient between gas and solid
        virtual tmp<volScalarField> KGasSolid
        (
            const phaseModel& gas,
            const phaseModel& solid
        ) const;

        //- Return the momentum transfer coefficient between liquid and solid
        virtual tmp<volScalarField> KLiquidSolid
        (
            const phaseModel& liquid,
            const phaseModel& solid
        ) const;


public:

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


    // Constructors

        //- Construct from a dictionary and a phase pair
        AttouFerschneider
        (
            const dictionary& dict,
            const phasePair& pair,
            const bool registerObject
        );


    //- Destructor
    virtual ~AttouFerschneider() = default;


    // Member Functions

        //- Drag coefficient
        virtual tmp<volScalarField> CdRe() const;

        //- The drag coefficient used in the momentum equation
        virtual tmp<volScalarField> K() const;

        //- The drag coefficient used in the face-momentum equations
        virtual tmp<surfaceScalarField> Kf() const;
};


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

} // End namespace dragModels
} // End namespace Foam

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

#endif

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