standardSA.H

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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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    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::RASModels::standardSA

Description
    Spalart-Allmaras one-eqn mixing-length model for incompressible and
    compressible external flows.

    Reference:
    \verbatim
        Spalart, P.R., & Allmaras, S.R. (1994).
        A one-equation turbulence model for aerodynamic flows.
        La Recherche Aerospatiale, 1, 5-21.
    \endverbatim

    The model is implemented without the trip-term, but maintaining the ft2
    term, considered as standard.

    Extended according to:
    \verbatim
        Allmaras, S. R., Johnson, F. T., & Spalart, P. R. (2012).
        Modifications and Clarifications for the Implementation of the
        Spalart-Allmaras Turbulence Model.
        ICCFD7-1902, 7th International Conference on Computational Fluid
        Dynamics, Big Island, Hawaii, 9-13 July 2012.
    \endverbatim

    using the optional flag \c neg

    It is necessary to limit the Stilda generation term as the model generates
    unphysical results if this term becomes negative which occurs for complex
    flow.  Several approaches have been proposed to limit Stilda but it is not
    clear which is the most appropriate.  Here the limiter proposed by Spalart
    is implemented in which Stilda is clipped at Cs*Omega with the default value
    of Cs = 0.3.

    The default model coefficients are
    \verbatim
        standardSACoeffs
        {
            Cb1         0.1355;
            Cb2         0.622;
            Cw2         0.3;
            Cw3         2.0;
            Cv1         7.1;
            Cv2         0.7;
            Cv3         0.9;
            Ct3         1.2;
            Ct4         0.5;
            Cn1         16.0;
            Cs          0.3;
            sigmaNut    0.66666;
            kappa       0.41;

            neg         false;
        }
    \endverbatim

SourceFiles
    standardSA.C

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

#ifndef standardSA_H
#define standardSA_H

#include "RASModel.H"
#include "eddyViscosity.H"

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

namespace Foam
{
namespace RASModels
{

/*---------------------------------------------------------------------------*\
                      Class standardSA Declaration
\*---------------------------------------------------------------------------*/

template<class BasicTurbulenceModel>
class standardSA
:
    public eddyViscosity<RASModel<BasicTurbulenceModel>>
{
protected:

    // Protected data

        // Model coefficients

            dimensionedScalar sigmaNut_;
            dimensionedScalar kappa_;

            dimensionedScalar Cb1_;
            dimensionedScalar Cb2_;
            dimensionedScalar Cw1_;
            dimensionedScalar Cw2_;
            dimensionedScalar Cw3_;
            dimensionedScalar Cv1_;
            dimensionedScalar Cv2_;
            dimensionedScalar Cv3_;
            dimensionedScalar Ct3_;
            dimensionedScalar Ct4_;
            dimensionedScalar Cn1_;
            dimensionedScalar Cs_;


        //- Optional flag to activate the negative nuTilda model
            Switch neg_;


        // Fields

            volScalarField nuTilda_;

            //- Wall distance
            //  Note: different to wall distance in parent RASModel
            //  which is for near-wall cells only
            const volScalarField& y_;


    // Protected Member Functions

        tmp<volScalarField> chi() const;

        tmp<volScalarField> fv1(const volScalarField& chi) const;

        tmp<volScalarField> fv2
        (
            const volScalarField& chi,
            const volScalarField& fv1
        ) const;

        tmp<volScalarField> ft2(const volScalarField& chi) const;

        tmp<volScalarField> Sbar
        (
            const volScalarField& chi,
            const volScalarField& fv1
        ) const;

        tmp<volScalarField> Stilda
        (
            const volScalarField& chi,
            const volScalarField& fv1
        ) const;

        tmp<volScalarField> fw(const volScalarField& Stilda) const;

        void correctNut(const volScalarField& fv1);
        virtual void correctNut();


public:

    typedef typename BasicTurbulenceModel::alphaField alphaField;
    typedef typename BasicTurbulenceModel::rhoField rhoField;
    typedef typename BasicTurbulenceModel::transportModel transportModel;


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


    // Constructors

        //- Construct from components
        standardSA
        (
            const alphaField& alpha,
            const rhoField& rho,
            const volVectorField& U,
            const surfaceScalarField& alphaRhoPhi,
            const surfaceScalarField& phi,
            const transportModel& transport,
            const word& propertiesName = turbulenceModel::propertiesName,
            const word& type = typeName
        );

        //- Disallow default bitwise copy construction
        standardSA(const standardSA&) = delete;


    //- Destructor
    virtual ~standardSA()
    {}


    // Member Functions

        //- Read RASProperties dictionary
        virtual bool read();

        //- Return the effective diffusivity for nuTilda
        tmp<volScalarField> DnuTildaEff(const volScalarField& chi) const;

        //- Return the turbulence kinetic energy
        virtual tmp<volScalarField> k() const;

        //- Return the turbulence kinetic energy dissipation rate
        virtual tmp<volScalarField> epsilon() const;

        //- Solve the turbulence equations and correct the turbulence viscosity
        virtual void correct();


    // Member Operators

        //- Disallow default bitwise assignment
        void operator=(const standardSA&) = delete;
};


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

} // End namespace RASModels
} // End namespace Foam

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

#ifdef NoRepository
    #include "standardSA.C"
#endif

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

#endif

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