/*---------------------------------------------------------------------------*\
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    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2017 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
    (at your option) any later version.

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    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::radiation::P1

Group
    grpRadiationModels

Description
    Works well for combustion applications where optical thickness, tau is
    large, i.e. tau = a*L > 3 (L = distance between objects)

    Assumes
     - all surfaces are diffuse
     - tends to over predict radiative fluxes from sources/sinks
       *** SOURCES NOT CURRENTLY INCLUDED ***

SourceFiles
    P1.C

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

#ifndef radiation_P1_H
#define radiation_P1_H

#include "radiationModel.H"
#include "volFields.H"

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

namespace Foam
{
namespace radiation
{

/*---------------------------------------------------------------------------*\
                           Class P1 Declaration
\*---------------------------------------------------------------------------*/

class P1
:
    public radiationModel
{
    // Private data

        //- Incident radiation / [W/m2]
        volScalarField G_;

        //- Total radiative heat flux [W/m2]
        volScalarField qr_;

        //- Absorption coefficient
        volScalarField a_;

        //- Emission coefficient
        volScalarField e_;

        //- Emission contribution
        volScalarField E_;


    // Private Member Functions

        //- No copy construct
        P1(const P1&) = delete;

        //- No copy assignment
        void operator=(const P1&) = delete;


public:

    //- Runtime type information
    TypeName("P1");


    // Constructors

        //- Construct from components
        P1(const volScalarField& T);

        //- Construct from components
        P1(const dictionary& dict, const volScalarField& T);


    //- Destructor
    virtual ~P1() = default;


    // Member functions

        // Edit

            //- Solve radiation equation(s)
            void calculate();

            //- Read radiation properties dictionary
            bool read();


        // Access

            //- Source term component (for power of T^4)
            virtual tmp<volScalarField> Rp() const;

            //- Source term component (constant)
            virtual tmp<volScalarField::Internal> Ru() const;

            //- Number of bands
            label nBands() const;
};


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

} // End namespace radiation
} // End namespace Foam

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

#endif

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