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Turbulence model modification

  • We modify the turbulence model in following way

     

  • Production of turbulent kinetic energy will be controlled using new constant $ C_{prod}$

     

  • Modified $ k$ $ -$ $ \epsilon$ model production term:

     

     

    $\displaystyle G = C_{prod} \nu_{t} S^{2}$(24.8)

     

     

  • New model constant $ C_{prod}$ will be read from constant/turbulenceProperties

     

  • Copy standard $ k$ $ -$ $ \epsilon$ model e.g. to directory models in your work directory:

    # cd $WM_PROJECT_USER_DIR
    # mkdir -p src/turbulenceModels/incompressible/RAS
    # cd $WM_PROJECT_USER_DIR/src/turbulenceModels/incompressible/RAS
    # cp -r $FOAM_SRC/TurbulenceModels/turbulenceModels/RAS/kEpsilon/ ./

     

  • New model can be called e.g. kEpsilonCprod model

     

  • Rename model:

    # mv kEpsilon kEpsilonCprod

     

  • Delete redundant file:

    # cd kEpsilonCprod
    # rm kEpsilon.dep

     

  • Rename model source files:

    $ {\textcolor{blue}{\mathsf {In \ Linux: }}}$
    # rename 's/kEpsilon/kEpsilonCprod/g' *
    $ {\textcolor{red}{\mathsf {In \ Windows: }}}$
    # rename kEpsilon kEpsilonCprod *

     

  • Replace name of the model also in files:

    # sed -i 's/kEpsilon/kEpsilonCprod/g' *

     

  • Create directory Make with configuration files:

    # cd ..
    # mkdir Make

     

  • In directory Make create file files:

     

    kEpsilonCprod/kEpsilonCprod.C

LIB = $(FOAM_USER_LIBBIN)/libuserincompressibleRASModels

     

  • In directory Make create file options:

     

    EXE_INC = \
    -I$(LIB_SRC)/TurbulenceModels/turbulenceModels/lnInclude \
    -I$(LIB_SRC)/TurbulenceModels/incompressible/lnInclude \
    -I$(LIB_SRC)/thermophysicalModels/basic/lnInclude \
    -I$(LIB_SRC)/transportModels \
    -I$(LIB_SRC)/transportModels/incompressible/lnInclude \
    -I$(LIB_SRC)/finiteVolume/lnInclude \
    -I$(LIB_SRC)/meshTools/lnInclude

LIB_LIBS = \
    -lturbulenceModels \
    -lincompressibleTurbulenceModels \
    -lfiniteVolume \
    -lmeshTools

     

  • Now we have just copied and renamed the model

     

  • In file kEpsilonCprod.H delete lines 211 -213

     

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

     

  • Compile model with no changes:

    # wmake

     

  • New library is created in dictionary $FOAM_USER_LIBBIN

    # ll $FOAM_USER_LIBBIN

     

  • Now implement the new model

     

  • Constant $ C_{prod}$ is read the same way as other model constants

     

  • Modify file kEpsilonCprod.H in the following way

     

  • Create variable for production control:

     

                dimensionedScalar Cmu_;
            dimensionedScalar C1_;
            dimensionedScalar C2_;
            dimensionedScalar C3_;
            dimensionedScalar sigmak_;
            dimensionedScalar sigmaEps_;
            dimensionedScalar Cprod_;

     

  • Modify the file kEpsilonCprod.C in the following way:

     

  • Create a new variable for $ C_{prod}$

     

        Cprod_
    (
        dimensioned<scalar>::lookupOrAddToDict
        (
            "Cprod",
            this->coeffDict_,
            1.0
        )
    ),

     

  • Modify function for reading model constants:

     

    bool kEpsilonCprod<BasicTurbulenceModel>::read()
{
    if (eddyViscosity<RASModel<BasicTurbulenceModel>>::read())
    {
        Cmu_.readIfPresent(this->coeffDict());
        C1_.readIfPresent(this->coeffDict());
        C2_.readIfPresent(this->coeffDict());
        C3_.readIfPresent(this->coeffDict());
        sigmak_.readIfPresent(this->coeffDict());
        sigmaEps_.readIfPresent(this->coeffDict());
        Cprod_.readIfPresent(this->coeffDict());

        return true;
    }
    else
    {
        return false;
    }
}

     

  • Modify function for computing production of turbulent kinetic energy:

     

            Cprod_*nut.v()*(dev(twoSymm(tgradU().v())) && tgradU().v())

     

  • Add modified turbulence model into turbulence models library:

     

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

#include "addToRunTimeSelectionTable.H"
#include "makeTurbulenceModel.H"
#include "RASModel.H"
#include "transportModel.H"
#include "incompressibleTurbulenceModel.H"
#include "IncompressibleTurbulenceModel.H"

namespace Foam
{
    typedef IncompressibleTurbulenceModel<transportModel> transportModelIncompressibleTurbulenceModel;
    typedef RASModel<transportModelIncompressibleTurbulenceModel> RAStransportModelIncompressibleTurbulenceModel;
}

makeTemplatedTurbulenceModel(transportModelIncompressibleTurbulenceModel, RAS, kEpsilonCprod)

     

  • Compile the new turbulence model:

    # wmake

  •  
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