| /*---------------------------------------------------------------------------*\ | |
| ========= | | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | |
| \\ / O peration | Website: https://openfoam.org | |
| \\ / A nd | Copyright (C) 2011-2026 OpenFOAM Foundation | |
| \\/ M anipulation | | |
| ------------------------------------------------------------------------------- | |
| 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::XiModel | |
| Description | |
| Base-class for all Xi models used by the b-Xi combustion model | |
| References: | |
| \verbatim | |
| Weller, H. G. (1993). | |
| The development of a new flame area combustion model | |
| using conditional averaging. | |
| Thermo-fluids section report TF 9307. | |
| Weller, H. G., Tabor, G., Gosman, A. D., & Fureby, C. (1998, January). | |
| Application of a flame-wrinkling LES combustion model | |
| to a turbulent mixing layer. | |
| In Symposium (International) on combustion | |
| (Vol. 27, No. 1, pp. 899-907). Elsevier. | |
| \endverbatim | |
| Xi is given through an algebraic expression (Foam::XiModels::algebraic), by | |
| solving a transport equation (Foam::XiModels::transport.H) or a fixed value | |
| (Foam::XiModels::fixed). | |
| In the algebraic and transport methods \f$\Xi_{eq}\f$ is calculated in | |
| similar way. In the algebraic approach, \f$\Xi_{eq}\f$ is the value used in | |
| the \f$ b \f$ transport equation. | |
| \f$\Xi_{eq}\f$ is calculated as follows: | |
| \f$\Xi_{eq} = 1 + (1 + 2\Xi_{coeff}(0.5 - \dwea{b}))(\Xi^* - 1)\f$ | |
| where: | |
| \f$ \dwea{b} \f$ is the regress variable. | |
| \f$ \Xi_{coeff} \f$ is a model constant. | |
| \f$ \Xi^* \f$ is the total equilibrium wrinkling combining the effects | |
| of the flame instability and turbulence interaction and is given by | |
| \f[ | |
| \Xi^* = \frac {R}{R - G_\eta - G_{in}} | |
| \f] | |
| where: | |
| \f$ G_\eta \f$ is the generation rate of wrinkling due to turbulence | |
| interaction. | |
| \f$ G_{in} = \kappa \rho_{u}/\rho_{b} \f$ is the generation | |
| rate due to the flame instability. | |
| By adding the removal rates of the two effects: | |
| \f[ | |
| R = G_\eta \frac{\Xi_{\eta_{eq}}}{\Xi_{\eta_{eq}} - 1} | |
| + G_{in} \frac{\Xi_{{in}_{eq}}}{\Xi_{{in}_{eq}} - 1} | |
| \f] | |
| where: | |
| \f$ R \f$ is the total removal. | |
| \f$ G_\eta \f$ is a model constant. | |
| \f$ \Xi_{\eta_{eq}} \f$ is the flame wrinkling due to turbulence. | |
| \f$ \Xi_{{in}_{eq}} \f$ is the equilibrium level of the flame wrinkling | |
| generated by instability. It is a constant (default 2.5). | |
| SourceFiles | |
| XiModel.C | |
| \*---------------------------------------------------------------------------*/ | |
| // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // | |
| namespace Foam | |
| { | |
| /*---------------------------------------------------------------------------*\ | |
| Class XiModel Declaration | |
| \*---------------------------------------------------------------------------*/ | |
| class XiModel | |
| { | |
| protected: | |
| // Protected data | |
| //- Thermo | |
| const ubRhoThermo& thermo_; | |
| //- Turbulence | |
| const compressibleMomentumTransportModel& momentumTransport_; | |
| const volScalarField& Su_; | |
| const volScalarField& rho_; | |
| const volScalarField& b_; | |
| //- Flame wrinkling field | |
| volScalarField Xi_; | |
| // Protected Member Functions | |
| //- Update coefficients from given dictionary | |
| virtual bool readCoeffs(const dictionary& dict) = 0; | |
| public: | |
| //- Runtime type information | |
| TypeName("XiModel"); | |
| // Declare run-time constructor selection table | |
| declareRunTimeSelectionTable | |
| ( | |
| autoPtr, | |
| XiModel, | |
| dictionary, | |
| ( | |
| const dictionary& dict, | |
| const ubRhoThermo& thermo, | |
| const compressibleMomentumTransportModel& turbulence, | |
| const volScalarField& Su | |
| ), | |
| ( | |
| dict, | |
| thermo, | |
| turbulence, | |
| Su | |
| ) | |
| ); | |
| // Constructors | |
| //- Construct from components | |
| XiModel | |
| ( | |
| const ubRhoThermo& thermo, | |
| const compressibleMomentumTransportModel& turbulence, | |
| const volScalarField& Su | |
| ); | |
| //- Disallow default bitwise copy construction | |
| XiModel(const XiModel&) = delete; | |
| // Selectors | |
| //- Return a reference to the selected Xi model | |
| static autoPtr<XiModel> New | |
| ( | |
| const dictionary& combustionProperties, | |
| const ubRhoThermo& thermo, | |
| const compressibleMomentumTransportModel& momentumTransport, | |
| const volScalarField& Su | |
| ); | |
| //- Destructor | |
| virtual ~XiModel(); | |
| // Member Functions | |
| //- Return the flame-wrinkling Xi | |
| virtual const volScalarField& Xi() const | |
| { | |
| return Xi_; | |
| } | |
| //- Return the flame diffusivity | |
| virtual tmp<volScalarField> Db() const = 0; | |
| //- Add Xi to the multivariateSurfaceInterpolationScheme table | |
| // if required | |
| virtual void addXi | |
| ( | |
| multivariateSurfaceInterpolationScheme<scalar>::fieldTable& | |
| ) | |
| {} | |
| //- Reset Xi to the unburnt state (1) | |
| virtual void reset(); | |
| //- Correct the flame-wrinkling Xi | |
| virtual void correct() = 0; | |
| //- Update properties from the given combustionProperties dictionary | |
| bool read(const dictionary& combustionProperties); | |
| // Member Operators | |
| //- Disallow default bitwise assignment | |
| void operator=(const XiModel&) = delete; | |
| }; | |
| // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // | |
| } // End namespace Foam | |
| // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // | |
| // ************************************************************************* // | |