1 /*---------------------------------------------------------------------------*\
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26 Foam::PDRDragModels::basic
29 Basic sub-grid obstacle drag model.
30 Details supplied by J Puttock 2/7/06.
32 <b> Sub-grid drag term </b>
34 The resistance term (force per unit of volume) is given by:
37 R = -\frac{1}{2} \rho \vert \dwea{\vec{U}} \vert \dwea{\vec{U}}.D
42 \f$ D \f$ is the tensor field "CR" in \f$ m^{-1} \f$
44 This is term is treated implicitly in UEqn.H
46 <b> Sub-grid turbulence generation </b>
48 The turbulence source term \f$ G_{R} \f$ occurring in the
49 \f$ \kappa-\epsilon \f$ equations for the generation of turbulence due
50 to interaction with unresolved obstacles :
52 \f$ G_{R} = C_{s}\beta_{\nu}
53 \mu_{eff} A_{w}^{2}(\dwea{\vec{U}}-\dwea{\vec{U}_{s}})^2 + \frac{1}{2}
54 \rho \vert \dwea{\vec{U}} \vert \dwea{\vec{U}}.T.\dwea{\vec{U}} \f$
60 \f$ \beta_{\nu} \f$ is the volume porosity (file "betav").
62 \f$ \mu_{eff} \f$ is the effective viscosity.
64 \f$ A_{w}^{2}\f$ is the obstacle surface area per unit of volume
67 \f$ \dwea{\vec{U}_{s}} \f$ is the slip velocity and is considered
68 \f$ \frac{1}{2}. \dwea{\vec{U}} \f$.
70 \f$ T \f$ is a tensor in the file CT.
72 The term \f$ G_{R} \f$ is treated explicitly in the \f$ \kappa-\epsilon
73 \f$ Eqs in the \link PDRkEpsilon.C \endlink file.
79 \*---------------------------------------------------------------------------*/
84 #include "PDRDragModel.H"
85 #include "XiEqModel.H"
90 namespace PDRDragModels
93 /*---------------------------------------------------------------------------*\
94 Class basic Declaration
95 \*---------------------------------------------------------------------------*/
103 dimensionedScalar Csu;
104 dimensionedScalar Csk;
107 volSymmTensorField CR_;
108 volSymmTensorField CT_;
111 // Private Member Functions
113 //- Disallow copy construct
116 //- Disallow default bitwise assignment
117 void operator=(const basic&);
122 //- Runtime type information
128 //- Construct from components
131 const dictionary& PDRProperties,
132 const compressible::RASModel& turbulence,
133 const volScalarField& rho,
134 const volVectorField& U,
135 const surfaceScalarField& phi
146 //- Return the momentum drag coefficient
147 virtual tmp<volSymmTensorField> Dcu() const;
149 //- Return the momentum drag turbulence generation rate
150 virtual tmp<volScalarField> Gk() const;
152 //- Update properties from given dictionary
153 virtual bool read(const dictionary& PDRProperties);
157 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
159 } // End namespace PDRDragModels
160 } // End namespace Foam
162 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
166 // ************************************************************************* //