isotropicDamping.H

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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::fv::isotropicDamping
 
Description
    This fvModel applies an implicit forcing force to all components of the
    vector field to relax the field towards a specified uniform value.  Its
    intended purpose is to damp the motions of an interface in the region
    approaching an outlet so that no reflections are generated.
 
    The forcing force coefficient \f$\lambda\f$ should be set based on the
    desired level of forcing and the residence time of a perturbation through
    the forcing zone.  For example, if waves moving at 2 [m/s] are travelling
    through a forcing zone 8 [m] in length, then the residence time is 4 [s]. If
    it is deemed necessary to damp for 5 time-scales, then \f$\lambda\f$ should
    be set to equal 5/(4 [s]) = 1.2 [1/s].
 
Usage
    Example usage:
    \verbatim
    isotropicDamping1
    {
        type            isotropicDamping;
 
        libs            ("libwaves.so");
 
        // Define the line along which to apply the graduation
        origin          (1200 0 0);
        direction       (1 0 0);
 
        // // Or, define multiple lines
        // origins         ((1200 0 0) (1200 -300 0) (1200 300 0));
        // directions      ((1 0 0) (0 -1 0) (0 1 0));
 
        scale
        {
            type        halfCosineRamp;
            start       0;
            duration    600;
        }
 
        value           (2 0 0);            // Value towards which the field is
                                            // relaxed
        lambda          [0 0 -1 0 0 0 0] 1; // Damping coefficient
 
        // Write the forcing fields: forcing:scale, forcing:forceCoeff
        writeForceFields true;
    }
    \endverbatim
 
See also
    Foam::fv::forcing
    Foam::fv::verticalDamping
 
SourceFiles
    isotropicDamping.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef isotropicDamping_H
#define isotropicDamping_H
 
#include "forcing.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace fv
{
 
/*---------------------------------------------------------------------------*\
                      Class isotropicDamping Declaration
\*---------------------------------------------------------------------------*/
 
class isotropicDamping
:
    public forcing
{
    // Private Data
 
        //- Name of the velocity field
        word UName_;
 
        //- Reference value
        dimensionedVector value_;
 
 
    // Private Member Functions
 
        //- Non-virtual read
        void readCoeffs();
 
        //- Source term to momentum equation
        void add
        (
            const volScalarField::Internal& forceCoeff,
            fvMatrix<vector>& eqn
        ) const;
 
 
public:
 
    //- Runtime type information
    TypeName("isotropicDamping");
 
 
    // Constructors
 
        //- Construct from components
        isotropicDamping
        (
            const word& name,
            const word& modelType,
            const fvMesh& mesh,
            const dictionary& dict
        );
 
 
    //- Destructor
    virtual ~isotropicDamping()
    {}
 
 
    // Member Functions
 
        //- Read dictionary
        virtual bool read(const dictionary& dict);
 
 
        // Checks
 
            //- Return the list of fields for which the fvModel adds source term
            //  to the transport equation
            virtual wordList addSupFields() const;
 
 
        // Add explicit and implicit contributions
 
            //- Source term to momentum equation
            virtual void addSup
            (
                const volVectorField& U,
                fvMatrix<vector>& eqn
            ) const;
 
            //- Source term to compressible momentum equation
            virtual void addSup
            (
                const volScalarField& rho,
                const volVectorField& U,
                fvMatrix<vector>& eqn
            ) const;
 
            //- Source term to phase momentum equation
            virtual void addSup
            (
                const volScalarField& alpha,
                const volScalarField& rho,
                const volVectorField& U,
                fvMatrix<vector>& eqn
            ) const;
 
 
        // Mesh changes
 
            //- Update for mesh motion
            virtual bool movePoints();
 
            //- Update topology using the given map
            virtual void topoChange(const polyTopoChangeMap&);
 
            //- Update from another mesh using the given map
            virtual void mapMesh(const polyMeshMap&);
 
            //- Redistribute or update using the given distribution map
            virtual void distribute(const polyDistributionMap&);
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace fv
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //