proudmanAcousticPower.H

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    Copyright (C) 2019-2021 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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    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::functionObjects::proudmanAcousticPower
 
Group
    grpFieldFunctionObjects
 
Description
    Computes the acoustic power due to the volume of isotropic turbulence
    using Proudman's formula.
 
    The acoustic power, i.e. \f$ P_A \f$ [\f$W/m^3\f$], in terms of turbulent
    kinetic energy, i.e. \f$ k \f$, and turbulent kinetic energy dissipation
    rate, i.e. \f$ \epsilon \f$, is given as:
 
        \f[
            P_A = \alpha_\epsilon \rho \epsilon M_t^5
        \f]
 
    where \f$ \alpha_\epsilon = 0.1 \f$ is a constant and
 
        \f[
            M_t = \frac{\sqrt{2 k}}{a_0}
        \f]
 
    with \f$ a_0 \f$ the speed of sound.  The acoustic power is also output in
    dB using:
 
        \f[
            L_P = 10 \log \frac{P_A}{P_{ref}}
        \f]
 
    where \f$ P_{ref} = 1e^{-12} \f$ [\f$W/m^3\f$] is a constant.
 
    Operands:
    \table
      Operand        | Type           | Location
      input          | volScalarField | <time>/inputField
      output file    | -              | -
      output field   | volScalarField | <time>/outputField
    \endtable
 
Usage
    Minimal example by using \c system/controlDict.functions:
    \verbatim
    proudmanAcousticPowerFO
    {
        // Mandatory entries
        type            proudmanAcousticPower;
        libs            (fieldFunctionObjects);
 
        // Optional entries
        alphaEps        <scalar>;
        // For incompressible flow simulations
        rhoInf          <scalar>;
        aRef            <scalar>;
        // Turbulence field names (if not retrieved from the turb model)
        k               <word>;
        epsilon         <word>;
        omega           <word>;
 
        // Inherited entries
        ...
    }
    \endverbatim
 
    where the entries mean:
    \table
      Property     | Description                         | Type | Reqd  | Deflt
      type         | Type name: proudmanAcousticPower    | word |  yes  | -
      libs         | Library name: fieldFunctionObjects  | word |  yes  | -
      rhoInf       | Freestream density (for incompressible) | scalar <!--
               --> | conditional | -
      aRef         | Speed of sound (incompressible)     | scalar <!--
               --> | conditional | -
      alphaEps     | Empirical model coefficient         | scalar | no  | 0.1
      k            | Turbulence k field name             | word | no    | none
      epsilon      | Turbulence epsilon field name       | word | no    | none
      omega        | Turbulence omega field name         | word | no    | none
    \endtable
 
    The inherited entries are elaborated in:
      - \link functionObject.H \endlink
 
Note
    The freestream density and reference speed of sound are only necessary
    when a thermodynamics package is unavailable, typically for incompressible
    cases.
 
SourceFiles
    proudmanAcousticPower.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef Foam_functionObjects_proudmanAcousticPower_H
#define Foam_functionObjects_proudmanAcousticPower_H
 
#include "fvMeshFunctionObject.H"
#include "volFieldsFwd.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace functionObjects
{
 
/*---------------------------------------------------------------------------*\
                   Class proudmanAcousticPower Declaration
\*---------------------------------------------------------------------------*/
 
class proudmanAcousticPower
:
    public fvMeshFunctionObject
{
    // Private Data
 
        //- Empirical model coefficient
        scalar alphaEps_;
 
        //- Freestream density (incompressible calcs only)
        dimensionedScalar rhoInf_;
 
        //- Reference speed of sound (incompressible calcs only)
        dimensionedScalar aRef_;
 
        //- Name of turbulence k field; default = none
        word kName_;
 
        //- Name of turbulence epsilon field; default = none
        word epsilonName_;
 
        //- Name of turbulence omega field; default = none
        word omegaName_;
 
 
    // Private Member Functions
 
        //- Multiply the field by density and return
        tmp<volScalarField> rhoScale(const tmp<volScalarField>& fld) const;
 
        //- Speed of sound
        tmp<volScalarField> a() const;
 
        //- Turbulence kinetic energy dissipation rate
        tmp<volScalarField> k() const;
 
        //- Turbulence dissipation
        tmp<volScalarField> epsilon() const;
 
 
public:
 
    //- Runtime type information
    TypeName("proudmanAcousticPower");
 
 
    // Constructors
 
        //- Construct from name, Time and dictionary
        proudmanAcousticPower
        (
            const word& name,
            const Time& runTime,
            const dictionary&
        );
 
        //- No copy construct
        proudmanAcousticPower(const proudmanAcousticPower&) = delete;
 
        //- No copy assignment
        void operator=(const proudmanAcousticPower&) = delete;
 
 
    //- Destructor
    virtual ~proudmanAcousticPower() = default;
 
 
    // Member Functions
 
        //- Read the function-object dictionary
        virtual bool read(const dictionary& dict);
 
        //- Execute the function-object operations
        virtual bool execute();
 
        //- Write the function-object results
        virtual bool write();
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace functionObjects
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //