fractal.H

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Class
    Foam::diameterModels::shapeModels::fractal

Description
    Class for modeling fractal shapes (e.g. of aerosol agglomerates) based on a
    constant fractal dimension and an average but field-dependent surface area
    to volume ratio kappa.

    The effect of sintering (coalescence of primary particles) on the surface
    area is taken into account by a separate source term.

    Kappa is transported between the size groups as a secondary property by
    means of coalescence (coagulation), breakup as well as drift.

    By assuming a monodisperse size distribution of the primary particles in the
    aggregate, the collisional diameter of a size group can then be computed by

    \f[
        d_{Coll_i} =
            \frac{6}{\kappa_i}
            \left(
                \frac{v_i \kappa_i^3}{36 \pi \alpha_c}
            \right)^{1/D_f}\;.
    \f]

Usage
    \table
        Property     | Description             | Required    | Default value
        kappa        | Field and BC value      | yes         |
        Df           | Fractal dimension       | yes         |
        alphaC       | Constant                | yes         |
    \endtable

SourceFiles
    fractal.C

\*---------------------------------------------------------------------------*/

#ifndef fractal_H
#define fractal_H

#include "SecondaryPropertyModel.H"
#include "shapeModel.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{
namespace diameterModels
{
namespace shapeModels
{

class sinteringModel;

/*---------------------------------------------------------------------------*\
                           Class fractal Declaration
\*---------------------------------------------------------------------------*/

class fractal
:
    public SecondaryPropertyModel<shapeModel>
{
public:

    // Public Data types

        //- Surface growth type enumeration
        enum surfaceGrowthTypes
        {
            sgHardSphere,
            sgParkRogak,
            sgConserved
        };

        //- Surface growth type names
        static const NamedEnum<surfaceGrowthTypes, 3> sgTypeNames_;


private:

    // Private Data

        //- Ratio of surface area to volume
        volScalarField kappa_;

        //- Fractal dimension
        dimensionedScalar Df_;

        //- Scaling prefactor
        dimensionedScalar alphaC_;

        //- Collisional diameter
        volScalarField dColl_;

        //- Explicit source
        volScalarField Su_;

        //- Sintering model
        autoPtr<sinteringModel> sinteringModel_;


    // Private Member Functions

        tmp<volScalarField> dColl() const;


public:

    //- Runtime type information
    TypeName("fractal");


    // Constructors

        //- Construct from dictionary and sizeGroup
        fractal
        (
            const dictionary& dict,
            const sizeGroup& group
        );

        //- Disallow default bitwise copy construction
        fractal(const fractal&) = delete;


    //- Destructor
    virtual ~fractal();


    // Member Functions

        // Access

            //- Return reference to secondary property field
            virtual const volScalarField& fld() const;

            //- Access to secondary property source
            virtual volScalarField& src();

            //- Return representative surface area of the sizeGroup
            virtual const tmp<volScalarField> a() const;

            //- Return representative diameter of the sizeGroup
            virtual const tmp<volScalarField> d() const
            {
                return dColl_;
            }

        // Edit

            //- Correct the collisional diameter
            virtual void correct();

            //- Add drift contribution to secondary property source
            virtual void addDrift
            (
                const volScalarField& Su,
                const sizeGroup& fu,
                const driftModel& model
            );


    // Member Operators

        //- Disallow default bitwise assignment
        void operator=(const fractal&) = delete;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace shapeModels
} // End namespace diameterModels
} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //