executed with foamRun for single region simulations of foamMultiRun for
multi-region simulations. Replaces XiFoam and all the corresponding
tutorials have been updated and moved to tutorials/modules/XiFluid.
Class
Foam::solvers::XiFluid
Description
Solver module for compressible premixed/partially-premixed combustion with
turbulence modelling.
Combusting RANS code using the b-Xi two-equation model.
Xi may be obtained by either the solution of the Xi transport
equation or from an algebraic expression. Both approaches are
based on Gulder's flame speed correlation which has been shown
to be appropriate by comparison with the results from the
spectral model.
Strain effects are encorporated directly into the Xi equation
but not in the algebraic approximation. Further work need to be
done on this issue, particularly regarding the enhanced removal rate
caused by flame compression. Analysis using results of the spectral
model will be required.
For cases involving very lean Propane flames or other flames which are
very strain-sensitive, a transport equation for the laminar flame
speed is present. This equation is derived using heuristic arguments
involving the strain time scale and the strain-rate at extinction.
the transport velocity is the same as that for the Xi equation.
Uses the flexible PIMPLE (PISO-SIMPLE) solution for time-resolved and
pseudo-transient and steady simulations.
Optional fvModels and fvConstraints are provided to enhance the simulation
in many ways including adding various sources, chemical reactions,
combustion, Lagrangian particles, radiation, surface film etc. and
constraining or limiting the solution.
Reference:
\verbatim
Greenshields, C. J., & Weller, H. G. (2022).
Notes on Computational Fluid Dynamics: General Principles.
CFD Direct Ltd.: Reading, UK.
\endverbatim
SourceFiles
XiFluid.C
See also
Foam::solvers::fluidSolver
Foam::solvers::isothermalFluid
258 lines
7.2 KiB
C++
258 lines
7.2 KiB
C++
/*---------------------------------------------------------------------------*\
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration | Website: https://openfoam.org
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\\ / A nd | Copyright (C) 2011-2022 OpenFOAM Foundation
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\\/ M anipulation |
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-------------------------------------------------------------------------------
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License
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This file is part of OpenFOAM.
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OpenFOAM is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
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Class
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Foam::XiModel
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Description
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Base-class for all Xi models used by the b-Xi combustion model.
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See Technical Report SH/RE/01R for details on the PDR modelling.
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Xi is given through an algebraic expression (\link algebraic.H \endlink),
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by solving a transport equation (\link transport.H \endlink) or a
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fixed value (\link fixed.H \endlink).
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See report TR/HGW/10 for details on the Weller two equations model.
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In the algebraic and transport methods \f$\Xi_{eq}\f$ is calculated in
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similar way. In the algebraic approach, \f$\Xi_{eq}\f$ is the value used in
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the \f$ b \f$ transport equation.
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\f$\Xi_{eq}\f$ is calculated as follows:
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\f$\Xi_{eq} = 1 + (1 + 2\Xi_{coeff}(0.5 - \dwea{b}))(\Xi^* - 1)\f$
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where:
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\f$ \dwea{b} \f$ is the regress variable.
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\f$ \Xi_{coeff} \f$ is a model constant.
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\f$ \Xi^* \f$ is the total equilibrium wrinkling combining the effects
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of the flame instability and turbulence interaction and is given by
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\f[
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\Xi^* = \frac {R}{R - G_\eta - G_{in}}
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\f]
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where:
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\f$ G_\eta \f$ is the generation rate of wrinkling due to turbulence
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interaction.
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\f$ G_{in} = \kappa \rho_{u}/\rho_{b} \f$ is the generation
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rate due to the flame instability.
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By adding the removal rates of the two effects:
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\f[
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R = G_\eta \frac{\Xi_{\eta_{eq}}}{\Xi_{\eta_{eq}} - 1}
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+ G_{in} \frac{\Xi_{{in}_{eq}}}{\Xi_{{in}_{eq}} - 1}
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\f]
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where:
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\f$ R \f$ is the total removal.
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\f$ G_\eta \f$ is a model constant.
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\f$ \Xi_{\eta_{eq}} \f$ is the flame wrinkling due to turbulence.
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\f$ \Xi_{{in}_{eq}} \f$ is the equilibrium level of the flame wrinkling
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generated by instability. It is a constant (default 2.5).
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SourceFiles
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XiModel.C
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\*---------------------------------------------------------------------------*/
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#ifndef XiModel_H
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#define XiModel_H
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#include "IOdictionary.H"
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#include "psiuMulticomponentThermo.H"
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#include "compressibleMomentumTransportModels.H"
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#include "multivariateSurfaceInterpolationScheme.H"
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#include "fvcDiv.H"
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#include "runTimeSelectionTables.H"
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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namespace Foam
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{
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/*---------------------------------------------------------------------------*\
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Class XiModel Declaration
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\*---------------------------------------------------------------------------*/
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class XiModel
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{
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protected:
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// Protected data
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dictionary XiModelCoeffs_;
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const psiuMulticomponentThermo& thermo_;
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const compressible::RASModel& turbulence_;
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const volScalarField& Su_;
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const volScalarField& rho_;
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const volScalarField& b_;
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const surfaceScalarField& phi_;
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//- Flame wrinkling field
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volScalarField Xi_;
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public:
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//- Runtime type information
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TypeName("XiModel");
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// Declare run-time constructor selection table
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declareRunTimeSelectionTable
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(
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autoPtr,
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XiModel,
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dictionary,
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(
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const dictionary& XiProperties,
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const psiuMulticomponentThermo& thermo,
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const compressible::RASModel& turbulence,
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const volScalarField& Su,
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const volScalarField& rho,
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const volScalarField& b,
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const surfaceScalarField& phi
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),
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(
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XiProperties,
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thermo,
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turbulence,
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Su,
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rho,
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b,
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phi
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)
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);
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// Constructors
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//- Construct from components
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XiModel
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(
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const dictionary& XiProperties,
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const psiuMulticomponentThermo& thermo,
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const compressible::RASModel& turbulence,
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const volScalarField& Su,
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const volScalarField& rho,
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const volScalarField& b,
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const surfaceScalarField& phi
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);
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//- Disallow default bitwise copy construction
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XiModel(const XiModel&);
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// Selectors
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//- Return a reference to the selected Xi model
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static autoPtr<XiModel> New
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(
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const dictionary& XiProperties,
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const psiuMulticomponentThermo& thermo,
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const compressible::RASModel& turbulence,
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const volScalarField& Su,
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const volScalarField& rho,
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const volScalarField& b,
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const surfaceScalarField& phi
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);
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//- Destructor
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virtual ~XiModel();
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// Member Functions
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//- Return the flame-wrinkling Xi
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virtual const volScalarField& Xi() const
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{
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return Xi_;
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}
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//- Return the flame diffusivity
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virtual tmp<volScalarField> Db() const
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{
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return volScalarField::New
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(
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"Db",
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turbulence_.rho()*turbulence_.nuEff()
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);
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}
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//- Add Xi to the multivariateSurfaceInterpolationScheme table
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// if required
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virtual void addXi
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(
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multivariateSurfaceInterpolationScheme<scalar>::fieldTable&
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)
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{}
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//- Correct the flame-wrinkling Xi
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virtual void correct() = 0;
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//- Correct the flame-wrinkling Xi using the given convection scheme
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virtual void correct(const fv::convectionScheme<scalar>&)
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{
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correct();
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}
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//- Update properties from given dictionary
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virtual bool read(const dictionary& XiProperties) = 0;
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//- Write fields related to Xi model
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virtual void writeFields() = 0;
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// Member Operators
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//- Disallow default bitwise assignment
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void operator=(const XiModel&) = delete;
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};
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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} // End namespace Foam
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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#endif
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// ************************************************************************* //
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