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This formulation provides C-grid like pressure-flux staggering on an
unstructured mesh which is hugely beneficial for Euler-Euler multiphase
equations as it allows for all forces to be treated in a consistent
manner on the cell-faces which provides better balance, stability and
accuracy. However, to achieve face-force consistency the momentum
transport terms must be interpolated to the faces reducing accuracy of
this part of the system but this is offset by the increase in accuracy
of the force-balance.
Currently it is not clear if this face-based momentum equation
formulation is preferable for all Euler-Euler simulations so I have
included it on a switch to allow evaluation and comparison with the
previous cell-based formulation. To try the new algorithm simply switch
it on, e.g.:
PIMPLE
{
nOuterCorrectors 3;
nCorrectors 1;
nNonOrthogonalCorrectors 0;
faceMomentum yes;
}
It is proving particularly good for bubbly flows, eliminating the
staggering patterns often seen in the air velocity field with the
previous algorithm, removing other spurious numerical artifacts in the
velocity fields and improving stability and allowing larger time-steps
For particle-gas flows the advantage is noticeable but not nearly as
pronounced as in the bubbly flow cases.
Please test the new algorithm on your cases and provide feedback.
Henry G. Weller
CFD Direct
246 lines
7.0 KiB
C++
246 lines
7.0 KiB
C++
/*---------------------------------------------------------------------------*\
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration |
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\\ / A nd | Copyright (C) 2013-2015 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::twoPhaseSystem
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Description
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SourceFiles
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twoPhaseSystem.C
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\*---------------------------------------------------------------------------*/
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#ifndef twoPhaseSystem_H
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#define twoPhaseSystem_H
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#include "IOdictionary.H"
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#include "phaseModel.H"
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#include "phasePair.H"
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#include "orderedPhasePair.H"
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#include "volFields.H"
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#include "surfaceFields.H"
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#include "dragModel.H"
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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namespace Foam
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{
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class virtualMassModel;
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class heatTransferModel;
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class liftModel;
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class wallLubricationModel;
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class turbulentDispersionModel;
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class blendingMethod;
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template <class modelType> class BlendedInterfacialModel;
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/*---------------------------------------------------------------------------*\
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Class twoPhaseSystem Declaration
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\*---------------------------------------------------------------------------*/
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class twoPhaseSystem
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:
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public IOdictionary
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{
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// Private data
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//- Reference to the mesh
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const fvMesh& mesh_;
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//- Phase model 1
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phaseModel phase1_;
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//- Phase model 2
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phaseModel phase2_;
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//- Total volumetric flux
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surfaceScalarField phi_;
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//- Dilatation term
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volScalarField dgdt_;
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//- Unordered phase pair
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autoPtr<phasePair> pair_;
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//- Phase pair for phase 1 dispersed in phase 2
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autoPtr<orderedPhasePair> pair1In2_;
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//- Phase pair for phase 2 dispersed in phase 1
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autoPtr<orderedPhasePair> pair2In1_;
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//- Blending methods
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HashTable<autoPtr<blendingMethod>, word, word::hash> blendingMethods_;
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//- Drag model
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autoPtr<BlendedInterfacialModel<dragModel> > drag_;
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//- Virtual mass model
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autoPtr<BlendedInterfacialModel<virtualMassModel> > virtualMass_;
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//- Heat transfer model
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autoPtr<BlendedInterfacialModel<heatTransferModel> > heatTransfer_;
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//- Lift model
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autoPtr<BlendedInterfacialModel<liftModel> > lift_;
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//- Wall lubrication model
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autoPtr<BlendedInterfacialModel<wallLubricationModel> >
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wallLubrication_;
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//- Wall lubrication model
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autoPtr<BlendedInterfacialModel<turbulentDispersionModel> >
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turbulentDispersion_;
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//-
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static dimensionedScalar zeroResidualAlpha_;
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// Private member functions
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//- Return the mixture flux
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tmp<surfaceScalarField> calcPhi() const;
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public:
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// Constructors
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//- Construct from fvMesh
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twoPhaseSystem(const fvMesh&, const dimensionedVector& g);
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//- Destructor
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virtual ~twoPhaseSystem();
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// Member Functions
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//- Return the mixture density
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tmp<volScalarField> rho() const;
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//- Return the mixture velocity
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tmp<volVectorField> U() const;
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//- Return the drag coefficient
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tmp<volScalarField> Kd() const;
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//- Return the face drag coefficient
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tmp<surfaceScalarField> Kdf() const;
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//- Return the virtual mass coefficient
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tmp<volScalarField> Vm() const;
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//- Return the face virtual mass coefficient
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tmp<surfaceScalarField> Vmf() const;
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//- Return the heat transfer coefficient
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tmp<volScalarField> Kh() const;
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//- Return the combined force (lift + wall-lubrication)
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tmp<volVectorField> F() const;
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//- Return the combined face-force (lift + wall-lubrication)
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tmp<surfaceScalarField> Ff() const;
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//- Return the turbulent diffusivity
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// Multiplies the phase-fraction gradient
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tmp<volScalarField> D() const;
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//- Solve for the two-phase-fractions
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void solve();
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//- Correct two-phase properties other than turbulence
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void correct();
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//- Correct two-phase turbulence
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void correctTurbulence();
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//- Read base phaseProperties dictionary
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bool read();
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// Access
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//- Return the residual phase-fraction for given phase
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// Used to stabilize the phase momentum as the phase-fraction -> 0
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const dimensionedScalar& residualAlpha
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const phaseModel& phase
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) const;
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//- Return the drag model for the given phase
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const dragModel& drag(const phaseModel& phase) const;
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//- Return the virtual mass model for the given phase
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const virtualMassModel& virtualMass(const phaseModel& phase) const;
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//- Return the surface tension coefficient
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const dimensionedScalar& sigma() const;
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//- Return the mesh
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inline const fvMesh& mesh() const;
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//- Return phase model 1
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inline const phaseModel& phase1() const;
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//- Return non-const access to phase model 1
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inline phaseModel& phase1();
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//- Return phase model 2
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inline const phaseModel& phase2() const;
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//- Return non-const access to phase model 2
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inline phaseModel& phase2();
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//- Return the phase not given as an argument
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inline const phaseModel& otherPhase(const phaseModel& phase) const;
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//- Return the mixture flux
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inline const surfaceScalarField& phi() const;
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//- Return non-const access to the the mixture flux
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inline surfaceScalarField& phi();
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//- Return the dilatation term
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inline const volScalarField& dgdt() const;
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//- Return non-const access to the dilatation parameter
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inline volScalarField& dgdt();
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};
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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} // End namespace Foam
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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#include "twoPhaseSystemI.H"
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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#endif
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// ************************************************************************* //
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