kEpsilon.H

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    Copyright (C) 2019-2021 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    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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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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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::kEpsilon
 
Group
    grpRASTurbulence
 
Description
    Standard k-epsilon turbulence model for incompressible and compressible
    flows including rapid distortion theory (RDT) based compression term.
 
    Reference:
    \verbatim
        Standard model:
            Launder, B. E., & Spalding, D. B. (1972).
            Lectures in mathematical models of turbulence.
 
            Launder, B. E., & Spalding, D. B. (1974).
            The numerical computation of turbulent flows.
            Computer methods in applied mechanics and engineering,
            3(2), 269-289.
 
        For the RDT-based compression term:
            El Tahry, S. H. (1983).
            k-epsilon equation for compressible reciprocating engine flows.
            Journal of Energy, 7(4), 345-353.
 
        Two-layer wall treatment to allow operation on low-Re grids:
            Jongen, T. and Marx, Y.P. (1997) “Design of an Unconditionally
            Stable, Positive Scheme for the k−epsilon and Two-Layer Turbulence
            Models”, Computers & Fluids, 26(5), 469-487.
    \endverbatim
 
    The default model coefficients are
    \verbatim
        kEpsilonCoeffs
        {
            Cmu                 0.09;
            C1                  1.44;
            C2                  1.92;
            C3                  -0.33;
            sigmak              1.0;
            sigmaEps            1.3;
            twoLayerTreatment   false;
 
            // If two twoLayerTreatment = true,
 
            // Critical turbulence Reynolds number marking the separation
            // of inner-layer and outer-layer. Can be adjusted from 50.0
            // (low-speed flows) to 200.0 (default value).
            ReyStar          200.0;
 
            // Smoothness of transition from inner-layer to outer-layer.
            // Typically from 0.05 (sharp transition) to 0.2 (smooth transition).
            // For unstable cases, prefer larger values.
            ReyFactor        0.05;
        }
    \endverbatim
 
SourceFiles
    kEpsilon.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef kEpsilon_H
#define kEpsilon_H
 
#include "RASModel.H"
#include "eddyViscosity.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace RASModels
{
 
/*---------------------------------------------------------------------------*\
                           Class kEpsilon Declaration
\*---------------------------------------------------------------------------*/
 
template<class BasicTurbulenceModel>
class kEpsilon
:
    public eddyViscosity<RASModel<BasicTurbulenceModel>>
{
    // Private Member Functions
 
        //- No copy construct
        kEpsilon(const kEpsilon&) = delete;
 
        //- No copy assignment
        void operator=(const kEpsilon&) = delete;
 
 
protected:
 
    // Protected data
 
        // Model coefficients
 
            dimensionedScalar Cmu_;
            dimensionedScalar C1_;
            dimensionedScalar C2_;
            dimensionedScalar C3_;
            dimensionedScalar sigmak_;
            dimensionedScalar sigmaEps_;
 
 
        // Fields
 
            volScalarField k_;
            volScalarField epsilon_;
 
 
        // Two-layer wall treatment
 
            bool twoLayerTreatment_;
            dimensionedScalar ReyStar_;
            dimensionedScalar ReyFactor_;
            std::unique_ptr<volScalarField::Internal> lEpsPtr_;
            std::unique_ptr<volScalarField> lambdaEpsPtr_;
 
 
    // Protected Member Functions
 
        virtual void correctNut();
        virtual tmp<fvScalarMatrix> kSource() const;
        virtual tmp<fvScalarMatrix> epsilonSource() const;
 
 
public:
 
    typedef typename BasicTurbulenceModel::alphaField alphaField;
    typedef typename BasicTurbulenceModel::rhoField rhoField;
    typedef typename BasicTurbulenceModel::transportModel transportModel;
 
 
    //- Runtime type information
    TypeName("kEpsilon");
 
 
    // Constructors
 
        //- Construct from components
        kEpsilon
        (
            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
        );
 
 
    //- Destructor
    virtual ~kEpsilon() = default;
 
 
    // Member Functions
 
        //- Re-read model coefficients if they have changed
        virtual bool read();
 
        //- Return the effective diffusivity for k
        tmp<volScalarField> DkEff() const
        {
            return tmp<volScalarField>::New
            (
                "DkEff",
                (this->nut_/sigmak_ + this->nu())
            );
        }
 
        //- Return the effective diffusivity for epsilon
        tmp<volScalarField> DepsilonEff() const
        {
            return tmp<volScalarField>::New
            (
                "DepsilonEff",
                (this->nut_/sigmaEps_ + this->nu())
            );
        }
 
        //- Return the turbulence kinetic energy
        virtual tmp<volScalarField> k() const
        {
            return k_;
        }
 
        //- Return the turbulence kinetic energy dissipation rate
        virtual tmp<volScalarField> epsilon() const
        {
            return epsilon_;
        }
 
        //- Solve the turbulence equations and correct the turbulence viscosity
        virtual void correct();
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace RASModels
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#ifdef NoRepository
    #include "kEpsilon.C"
#endif
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //