kEpsilon.H

Go to the documentation of this file.

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
-------------------------------------------------------------------------------
    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2019-2021 OpenCFD Ltd.
-------------------------------------------------------------------------------
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.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    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::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

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