DMD.H

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    Copyright (C) 2023 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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Class
    Foam::ROMmodels::DMD
 
Description
    Field creation model using the streaming total dynamic mode
    decomposition method (STDMD).
 
    The governing equations of the field creation are as follows:
 
    \f[
        \mathbf{x}_\tau \approx
        \tilde{\mathbf{x}_\tau} =
        \left( \sum_{i=0}^{N-1} \phi_i \alpha_i v_i^\tau \right)_{real}
    \f]
 
    with
 
    \f[
        \tau = \frac{t - t_o}{\Delta t}
    \f]
 
    where:
 
    \vartable
        \mathbf{x}    | Field snapshot at time t
        \tilde{\mathbf{x}} | Reconstructed field snapshot at time t (complex)
        N             | Number of modes
        i             | Mode index
        \tau          | Nondimensional time
        t             | Time [s]
        t_o           | Start time (of mode decomposition calculations) [s]
        \Delta t      | Time-step size of mode decomposition [s]
        \phi          | Mode (complex)
        \alpha        | Mode amplitude (complex)
        v             | Mode eigenvalue (complex)
    \endvartable
 
    References:
    \verbatim
        Governing equations (tag:K):
            Kiewat, M. (2019).
            Streaming modal decomposition approaches for vehicle aerodynamics.
            PhD thesis. Munich: Technical University of Munich.
            URL:mediatum.ub.tum.de/doc/1482652/1482652.pdf
    \endverbatim
 
    Operands:
    \table
      Operand      | Type                 | Location
      input        | {vol,surface}<Type>Field | <time>/<inpField>
      output file  | -                    | -
      output field | {vol,surface}<Type>Field | <time>/<outField>
    \endtable
 
    where \c <Type>=Scalar/Vector/SphericalTensor/SymmTensor/Tensor.
 
Usage
    Minimal example by using \c system/ROMfieldsDict:
    \verbatim
        // Mandatory entries
        field           <word>;
        object          <word>;
        deltaT          <scalar>;
        time            <scalar>;
        modes           <labelList>;
        amplitudes      <complexList>;
        eigenvalues     <complexList>;
 
        // Optional entries
        startTime       <scalar>;
        dimensions      <dimensionSet>;
    \endverbatim
 
    where the entries mean:
    \table
      Property     | Description                        | Type | Reqd  | Deflt
      field        | Name of reconstructed field        | word | yes   | -
      object       | Name of operand function object    | word | yes   | -
      deltaT       | Time-step size of mode decomposition | scalar | yes | -
      time         | Time instant where modes are located | scalar | yes | -
      modes        | List of mode indices               | labelList | yes | -
      amplitudes   | Amplitude coefficients             | complexList | yes | -
      eigenvalues  | Eigenvalues                        | complexList | yes | -
      startTime | Start time for mode-information collection | scalar | no | 0
      dimensions | Dimensions of reconstructed fields | dimensionSet | no | -
    \endtable
 
SourceFiles
    DMD.C
    DMDImpl.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef ROMmodels_DMD_H
#define ROMmodels_DMD_H
 
#include "ROMmodels/ROMmodel/ROMmodel.H"
#include "dimensionSet.H"
#include "complex.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace ROMmodels
{
/*---------------------------------------------------------------------------*\
                            Class DMD Declaration
\*---------------------------------------------------------------------------*/
 
class DMD
:
    public ROMmodel
{
    // Private Typedefs
 
        typedef List<complex> complexList;
 
 
    // Private Data
 
        //- Name of reconstructed field
        word fieldName_;
 
        //- Name of operand function object
        word objectName_;
 
        //- Time-step size of mode decomposition (not that of the simulation)
        scalar deltaT_;
 
        //- Time instant where modes are located
        scalar time_;
 
        //- Start time for mode-information collection
        scalar startTime_;
 
        //- List of mode indices
        labelList modes_;
 
        //- Dimensions of reconstructed fields
        dimensionSet dims_;
 
        //- Amplitude coefficients
        complexList amps_;
 
        //- Eigenvalues
        complexList evals_;
 
 
    // Private Member Functions
 
        //- Return names of mode fields
        wordList modeNames(const word& modeType) const;
 
        //- Implementation for creating and writing fields
        template<class GeoType>
        bool createAndWriteImpl() const;
 
 
public:
 
    //- Runtime type information
    TypeName("DMD");
 
 
    // Constructors
 
        //- Construct from components
        DMD
        (
            Time& runTime,
            fvMesh& mesh,
            const dictionary& dict,
            const instantList& times
        );
 
        //- No copy construct
        DMD(const DMD&) = delete;
 
        //- No copy assignment
        void operator=(const DMD&) = delete;
 
 
    //- Destructor
    virtual ~DMD() = default;
 
 
    // Member Functions
 
        //- Read model settings
        virtual bool read(const dictionary& dict);
 
        //- Create and write fields
        virtual bool createAndWrite();
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace ROMmodels
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //