XiModel.H

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Class
    Foam::XiModel
 
Description
    Base-class for all Xi models used by the b-Xi combustion model
 
    References:
    \verbatim
        Weller, H. G. (1993).
        The development of a new flame area combustion model
        using conditional averaging.
        Thermo-fluids section report TF 9307.
 
        Weller, H. G., Tabor, G., Gosman, A. D., & Fureby, C. (1998, January).
        Application of a flame-wrinkling LES combustion model
        to a turbulent mixing layer.
        In Symposium (International) on combustion
        (Vol. 27, No. 1, pp. 899-907). Elsevier.
    \endverbatim
 
    Xi is given through an algebraic expression (Foam::XiModels::algebraic), by
    solving a transport equation (Foam::XiModels::transport.H) or a fixed value
    (Foam::XiModels::fixed).
 
    In the algebraic and transport methods \f$\Xi_{eq}\f$ is calculated in
    similar way. In the algebraic approach, \f$\Xi_{eq}\f$ is the value used in
    the \f$ b \f$ transport equation.
 
    \f$\Xi_{eq}\f$ is calculated as follows:
 
    \f$\Xi_{eq} = 1 + (1 + 2\Xi_{coeff}(0.5 - \dwea{b}))(\Xi^* - 1)\f$
 
    where:
 
        \f$ \dwea{b} \f$ is the regress variable.
 
        \f$ \Xi_{coeff} \f$ is a model constant.
 
        \f$ \Xi^* \f$ is the total equilibrium wrinkling combining the effects
        of the flame instability and turbulence interaction and is given by
 
        \f[
            \Xi^* = \frac {R}{R - G_\eta - G_{in}}
        \f]
 
    where:
 
        \f$ G_\eta \f$ is the generation rate of wrinkling due to turbulence
        interaction.
 
        \f$ G_{in} = \kappa \rho_{u}/\rho_{b} \f$ is the generation
         rate due to the flame instability.
 
    By adding the removal rates of the two effects:
 
        \f[
            R = G_\eta \frac{\Xi_{\eta_{eq}}}{\Xi_{\eta_{eq}} - 1}
              + G_{in} \frac{\Xi_{{in}_{eq}}}{\Xi_{{in}_{eq}} - 1}
        \f]
 
    where:
 
        \f$ R \f$ is the total removal.
 
        \f$ G_\eta \f$ is a model constant.
 
        \f$ \Xi_{\eta_{eq}} \f$ is the flame wrinkling due to turbulence.
 
        \f$ \Xi_{{in}_{eq}} \f$ is the equilibrium level of the flame wrinkling
        generated by instability. It is a constant (default 2.5).
 
 
SourceFiles
    XiModel.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef XiModel_H
#define XiModel_H
 
#include "psiuMulticomponentThermo.H"
#include "fluidThermoThermophysicalTransportModels.H"
#include "runTimeSelectionTables.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
/*---------------------------------------------------------------------------*\
                           Class XiModel Declaration
\*---------------------------------------------------------------------------*/
 
class XiModel
{
 
protected:
 
    // Protected data
 
        //- Thermo
        const psiuMulticomponentThermo& thermo_;
 
        //- Thermo-physical transport
        const fluidThermoThermophysicalTransportModel& thermoTransport_;
 
        //- Turbulence
        const compressibleMomentumTransportModel& turbulence_;
 
        const volScalarField& Su_;
 
        const volScalarField& rho_;
 
        const volScalarField& b_;
 
        //- Flame wrinkling field
        volScalarField Xi_;
 
 
    // Protected member functions
 
        //- Update coefficients from given dictionary
        virtual bool readCoeffs(const dictionary& dict) = 0;
 
 
public:
 
    //- Runtime type information
    TypeName("XiModel");
 
 
    // Declare run-time constructor selection table
 
        declareRunTimeSelectionTable
        (
            autoPtr,
            XiModel,
            dictionary,
            (
                const dictionary& dict,
                const psiuMulticomponentThermo& thermo,
                const fluidThermoThermophysicalTransportModel& turbulence,
                const volScalarField& Su
            ),
            (
                dict,
                thermo,
                turbulence,
                Su
            )
        );
 
 
    // Constructors
 
        //- Construct from components
        XiModel
        (
            const psiuMulticomponentThermo& thermo,
            const fluidThermoThermophysicalTransportModel& turbulence,
            const volScalarField& Su
        );
 
        //- Disallow default bitwise copy construction
        XiModel(const XiModel&) = delete;
 
 
    // Selectors
 
        //- Return a reference to the selected Xi model
        static autoPtr<XiModel> New
        (
            const dictionary& combustionProperties,
            const psiuMulticomponentThermo& thermo,
            const fluidThermoThermophysicalTransportModel& turbulence,
            const volScalarField& Su
        );
 
 
    //- Destructor
    virtual ~XiModel();
 
 
    // Member Functions
 
        //- Return the flame-wrinkling Xi
        virtual const volScalarField& Xi() const
        {
            return Xi_;
        }
 
        //- Return the flame diffusivity
        virtual tmp<volScalarField> Db() const
        {
            return volScalarField::New
            (
                "Db",
                turbulence_.rho()*turbulence_.nuEff()
            );
        }
 
        //- Add Xi to the multivariateSurfaceInterpolationScheme table
        //  if required
        virtual void addXi
        (
            multivariateSurfaceInterpolationScheme<scalar>::fieldTable&
        )
        {}
 
        //- Reset Xi to the unburnt state (1)
        virtual void reset();
 
        //- Correct the flame-wrinkling Xi
        virtual void correct() = 0;
 
        //- Update properties from the given combustionProperties dictionary
        bool read(const dictionary& combustionProperties);
 
 
    // Member Operators
 
        //- Disallow default bitwise assignment
        void operator=(const XiModel&) = delete;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //