actuationDiskSource.H

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    Copyright (C) 2020 ENERCON GmbH
    Copyright (C) 2020 OpenCFD Ltd.
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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.
 
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    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::actuationDiskSource
 
Group
    grpFvOptionsSources
 
Description
    Applies sources on velocity, i.e. \c U, to enable actuator disk models
    for aero/hydro thrust loading of horizontal axis turbines on surrounding
    flow field in terms of energy conversion processes.
 
    Available options for force computations:
    \verbatim
      Froude          | Froude's one-dimensional ideal actuator disk method
      variableScaling | Variable-scaling actuator disk method
    \endverbatim
 
    The expressions for \c Froude method:
    \f[
        T = 2 \rho A | \vec{U_o} \cdot \vec{n} |^2 a (1-a)
    \f]
    with
    \f[
        a = 1 - \frac{C_p}{C_T}
    \f]
    where
    \vartable
      T         | Thrust magnitude
      \rho      | Monitored incoming fluid density
      A         | Actuator disk planar surface area
      \vec{U_o} | Incoming velocity spatial-averaged on monitored region
      \vec{n}   | Surface-normal vector of the actuator disk pointing upstream
      a         | Axial induction factor
      C_p       | Power coefficient
      C_T       | Thrust coefficient
    \endvartable
 
    The expressions for \c variableScaling method:
    \f[
        T = 0.5 \rho A | \vec{U_m} \cdot \vec{n} |^2 C_T^*
    \f]
    with
    \f[
        C_T^* = C_T \left( \frac{ |\vec{U_{ref}}| }{ |\vec{U_m}| } \right)^2
    \f]
    where
    \vartable
        T         | Thrust magnitude
        \rho      | Monitored incoming fluid density
        A         | Actuator disk planar surface area
        \vec{U_m} | Incoming velocity spatial-averaged on actuator disk
        \vec{n}   | Surface-normal vector of the actuator disk pointing upstream
        \vec{U_{ref}} | Incoming velocity spatial-averaged on monitored region
        C_T       | Thrust coefficient
        C_T^*     | Calibrated thrust coefficient
    \endvartable
 
    Reference
    \verbatim
        Froude's one-dimensional ideal actuator disk (tags:F,BJSB):
            Froude, R. E. (1889).
            On the part played in propulsion by differences of fluid pressure.
            Trans. Inst. Naval Architects, 30, 390.
 
            Burton, T., Jenkins, N., Sharpe, D., & Bossanyi, E. (2011).
            Wind energy handbook, 2nd edition.
            Chichester, the United Kingdom. John Wiley & Sons.
            Print ISBN:978-0-470-69975-1
            DOI:10.1002/9781119992714
 
        Variable-scaling method (tags:LSRMKT,LS):
            van der Laan, M. P., Sørensen, N. N., Réthoré, P. E.,
            Mann, J., Kelly, M. C., & Troldborg, N. (2015).
            The k‐ε‐fP model applied to double wind turbine
            wakes using different actuator disk force methods.
            Wind Energy, 18(12), 2223-2240.
            DOI:10.1002/we.1816
 
            van der Laan, M. P., Sørensen, N. N., Réthoré, P. E., Mann, J.,
            Kelly, M. C., Troldborg, N., Hansen, K. S., & Murcia, J. P. (2015).
            The k‐ε‐fP model applied to wind farms.
            Wind Energy, 18(12), 2065-2084.
            DOI:10.1002/we.1804
    \endverbatim
 
    Corrections applied to:
    \verbatim
      U         | Velocity    [m/s]
    \endverbatim
 
    Required fields:
    \verbatim
      U         | Velocity    [m/s]
    \endverbatim
 
Usage
    Example by using \c constant/fvOptions:
    \verbatim
    actuationDiskSource1
    {
        // Mandatory entries (unmodifiable)
        type            actuationDiskSource;
 
        // Mandatory (inherited) entries (unmodifiable)
        selectionMode   <mode>;    // e.g. cellSet as shown below
        cellSet         <cellSetName>;
 
        // Mandatory entries (runtime modifiable)
        diskArea        40.0;
        diskDir         (1 0 0);
        Cp              <Function1>;
        Ct              <Function1>;
 
        // Conditional optional entries (unmodifiable)
        monitorMethod   <points|cellSet>;
        monitorCoeffs
        {
            // Option-1
            points
            (
                (p1x p1y p1z)
                (p2x p2y p2z)
                ...
            );
 
            // Option-2
            cellSet     <monitorCellSet>;
        }
 
        // Optional entries (unmodifiable)
        variant         <forceMethod>;
 
        // Optional entries (runtime modifiable)
        sink            true;
        writeFileStart  0;
        writeFileEnd    100;
 
        // Optional (inherited) entries
        ...
    }
    \endverbatim
 
    where the entries mean:
    \table
      Property   | Description                         | Type | Req'd    | Dflt
      type       | Type name: actuationDiskSource      | word | yes      | -
      diskArea   | Actuator disk planar surface area   | scalar | yes | -
      diskDir    | Surface-normal vector of the actuator disk <!--
               --> pointing upstream                   | vector    | yes | -
      Cp         | Power coefficient                   | Function1 | yes | -
      Ct         | Thrust coefficient                  | Function1 | yes | -
      monitorMethod | Type of incoming velocity monitoring method   <!--
               -->    - see below                      | word | no  | points
      variant    | Type of the force computation method - see below <!--
               -->                                     | word | no  | Froude
      sink        | Flag for body forces to act as a source (true)  <!--
               -->  or a sink (false)                  | bool   | no  | true
      writeFileStart | Start time for file output      | scalar | no  | 0
      writeFileEnd   | End time for file output        | scalar | no  | VGREAT
    \endtable
 
    The inherited entries are elaborated in:
      - \link fvOption.H \endlink
      - \link cellSetOption.H \endlink
      - \link writeFile.H \endlink
      - \link Function1.H \endlink
 
    Options for the \c monitorMethod entry:
    \verbatim
      points  | Monitor incoming velocity field at a given set of points
      cellSet | Monitor incoming velocity field at a given cellSet
    \endverbatim
 
    Options for the \c variant entry:
    \verbatim
      Froude          | Froude's one-dimensional ideal actuator disk method
      variableScaling | Variable-scaling actuator disk method
    \endverbatim
 
SourceFiles
    actuationDiskSource.C
    actuationDiskSourceTemplates.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef actuationDiskSource_H
#define actuationDiskSource_H
 
#include "cellSetOption.H"
#include "writeFile.H"
#include "Function1.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace fv
{
 
/*---------------------------------------------------------------------------*\
                     Class actuationDiskSource Declaration
\*---------------------------------------------------------------------------*/
 
class actuationDiskSource
:
    public cellSetOption,
    public functionObjects::writeFile
{
protected:
 
    // Protected Enumerations
 
        //- Options for the force computation method types
        enum forceMethodType
        {
            FROUDE,                 
            VARIABLE_SCALING,       
        };
 
        //- Names for forceMethodType
        static const Enum<forceMethodType> forceMethodTypeNames;
 
        //- Options for the incoming velocity monitoring method types
        enum monitorMethodType
        {
            POINTS,                 
            CELLSET                 
        };
 
        //- Names for monitorMethodType
        static const Enum<monitorMethodType> monitorMethodTypeNames;
 
 
    // Protected Data
 
        //- The type of the force computation method
        const enum forceMethodType forceMethod_;
 
        //- The type of incoming velocity monitoring method
        const enum monitorMethodType monitorMethod_;
 
        //- Flag for body forces to act as a source (true) or a sink (false)
        label sink_;
 
        //- Start time for file output
        scalar writeFileStart_;
 
        //- End time for file output
        scalar writeFileEnd_;
 
        //- Actuator disk planar surface area [m2]
        scalar diskArea_;
 
        //- Surface-normal vector of the actuator disk pointing upstream
        vector diskDir_;
 
        //- Velocity vs power coefficients
        autoPtr<Function1<scalar>> UvsCpPtr_;
 
        //- Velocity vs thrust coefficients
        autoPtr<Function1<scalar>> UvsCtPtr_;
 
        //- Set of cells whereat the incoming velocity is monitored
        labelList monitorCells_;
 
 
    // Protected Member Functions
 
        //- Output file header information
        virtual void writeFileHeader(Ostream& os);
 
 
private:
 
    // Private Member Functions
 
        //- Locate the set of cells whereat the incoming velocity is monitored
        void setMonitorCells(const dictionary& dict);
 
        //- Compute the selected force computation method type
        template<class AlphaFieldType, class RhoFieldType>
        void calc
        (
            const AlphaFieldType& alpha,
            const RhoFieldType& rho,
            fvMatrix<vector>& eqn
        );
 
        //- Compute Froude's ideal actuator disk method
        template<class AlphaFieldType, class RhoFieldType>
        void calcFroudeMethod
        (
            const AlphaFieldType& alpha,
            const RhoFieldType& rho,
            fvMatrix<vector>& eqn
        );
 
        //- Compute variable-scaling actuator disk method
        template<class AlphaFieldType, class RhoFieldType>
        void calcVariableScalingMethod
        (
            const AlphaFieldType& alpha,
            const RhoFieldType& rho,
            fvMatrix<vector>& eqn
        );
 
 
public:
 
    //- Runtime type information
    TypeName("actuationDiskSource");
 
 
    // Constructors
 
        //- Construct from components
        actuationDiskSource
        (
            const word& name,
            const word& modelType,
            const dictionary& dict,
            const fvMesh& mesh
        );
 
        //- No copy construct
        actuationDiskSource(const actuationDiskSource&) = delete;
 
        //- No copy assignment
        void operator=(const actuationDiskSource&) = delete;
 
 
    //- Destructor
    virtual ~actuationDiskSource() = default;
 
 
    // Member Functions
 
        // Access
 
            //- Normal disk direction
            const vector& diskDir() const
            {
                return diskDir_;
            }
 
            //- Disk area
            scalar diskArea() const
            {
                return diskArea_;
            }
 
 
         // Add explicit and implicit contributions
 
            //- Source term to momentum equation
            virtual void addSup
            (
                fvMatrix<vector>& eqn,
                const label fieldi
            );
 
            //- Source term to compressible momentum equation
            virtual void addSup
            (
                const volScalarField& rho,
                fvMatrix<vector>& eqn,
                const label fieldi
            );
 
            //- Source term to phase-compressible momentum equation
            virtual void addSup
            (
                const volScalarField& alpha,
                const volScalarField& rho,
                fvMatrix<vector>& eqn,
                const label fieldi
            );
 
 
        // IO
 
            //- Read dictionary
            virtual bool read(const dictionary& dict);
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace fv
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#ifdef NoRepository
    #include "actuationDiskSourceTemplates.C"
#endif
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //