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                    \\     ||  | Multiphase Code Repository by HZDR
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  ||  ||  //    ||  // || \\   | License: GPL-3.0-or-later
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License
    This file is part of the Multiphase Code Repository by HZDR.

    Copyright (C) 2025 by Helmholtz-Zentrum Dresden-Rossendorf e.V. (HZDR),
    Website: https://hzdr.de

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Class
    Foam::dragModels::constantDragCoefficient

Description
    Numerical drag model for bubbly flows. The drag law is formulated with a
    constant coefficient Cd, which has to be defined by the user.

Interfacial momentum transfer due to drag
\f[
    \vec{M}_d = -\vec{M}_c = K\,\left(\vec{U}_c-\vec{U}_d\right)
\f]

Drag function K
\f[
    K = \alpha_d Ki
\f]

Phase specific drag function Ki
\f[
    Ki = 0.75 CdRe\rho_c\nu_c/d^2
\f]

Combined drag coefficient and Reynolds number CdRe
\f[
    CdRe = c_d max(Re, Re_{res})
\f]

Usage
    \table
        Parameter      | Name       | Description        | Default value
        \f$c_d\f$      | Cd         | drag coefficient   | -
        \f$Re_{res}\f$ | residualRe | minimal applied Re | -
    \endtable

SourceFiles
    constantDragCoefficient.C

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

#ifndef constantDragCoefficient_H
#define constantDragCoefficient_H

#include "dispersedDragModel.H"

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

namespace Foam
{
namespace dragModels
{

/*---------------------------------------------------------------------------*\
                   Class constantDragCoefficient Declaration
\*---------------------------------------------------------------------------*/

class constantDragCoefficient
:
    public dispersedDragModel
{
    // Private Data

        //- Drag coefficient
        const dimensionedScalar Cd_;

        //- Residual Reynolds Number
        const dimensionedScalar residualRe_;


public:

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


    // Constructors

        //- Construct from a dictionary and an interface
        constantDragCoefficient
        (
            const dictionary& dict,
            const phaseInterface& interface,
            const bool registerObject
        );


    //- Destructor
    virtual ~constantDragCoefficient();


    // Member Functions

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


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

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

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

#endif

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