Computes film-separation properties from sharp edges for full separation (Friedrich et al., 2008) and partial separation (Zhang et al., 2018). More...

Inheritance diagram for FriedrichModel:

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Collaboration diagram for FriedrichModel:

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Public Member Functions
	TypeName ("Friedrich")
	Runtime type information. More...

	FriedrichModel (const regionModels::areaSurfaceFilmModels::liquidFilmBase &film, const dictionary &dict)
	Construct from the base film model and dictionary. More...

virtual	~FriedrichModel ()=default

virtual tmp< scalarField >	separatedMassRatio () const
	Calculate the mass ratio of film separation. More...

Public Member Functions inherited from filmSeparationModel
	TypeName ("filmSeparationModel")
	Runtime type information. More...

	declareRunTimeSelectionTable (autoPtr, filmSeparationModel, dictionary,(const regionModels::areaSurfaceFilmModels::liquidFilmBase &film, const dictionary &dict),(film, dict))

	filmSeparationModel (const filmSeparationModel &)=delete
	No copy construct. More...

void	operator= (const filmSeparationModel &)=delete
	No copy assignment. More...

	filmSeparationModel (const regionModels::areaSurfaceFilmModels::liquidFilmBase &film, const dictionary &dict)
	Construct from the base film model and dictionary. More...

virtual	~filmSeparationModel ()=default
	Destructor. More...

const regionModels::areaSurfaceFilmModels::liquidFilmBase &	film () const
	Return const access to the film properties. More...

const faMesh &	mesh () const noexcept
	Return const access to the finite-area mesh. More...

Additional Inherited Members
Static Public Member Functions inherited from filmSeparationModel
static autoPtr< filmSeparationModel >	New (const regionModels::areaSurfaceFilmModels::liquidFilmBase &film, const dictionary &dict)
	Return a reference to the selected filmSeparation model. More...

Detailed Description

Computes film-separation properties from sharp edges for full separation (Friedrich et al., 2008) and partial separation (Zhang et al., 2018).

The governing equations for full separation (Friedrich et al., 2008):

$F_{ratio} = \frac{\rho \, |\vec{u}|^2 \, h \, sin(\theta)} {\sigma (1 + sin(\theta)) + \rho \, \mathbf{g}\, h\,L_b cos(\theta)}$

with:

$L_b = 0.0388 h^{0.5} \mathrm{Re}^{0.6} \mathrm{We}^{-0.5}$

$\mathrm{Re} = \frac{h \, |\vec{u}| \, \rho}{\mu}$

$\mathrm{We} = \frac{h \, \rho_p (\vec{u}_p - \vec{u})^2}{2 \sigma}$

where:

$F_{ratio}$	=	Force ratio
	=	Film thickness
$\rho$	=	Film density
$\rho_p$	=	Primary-phase (gas) density
$\sigma$	=	Film surface tension
$\mu$	=	Film dynamic viscosity
$\mathbf{u}$	=	Film velocity
$\mathbf{g}$	=	Gravitational acceleration
$\theta$	=	Sharp-corner angle
	=	Characteristic breakup length

The onset of film separation is triggered and the film is assumed fully separated when $F_{ratio}>1$ ; otherwise, it remains attached.

The governing equations for partial separation (Zhang et al., 2018):

$m_{ratio} = C_0 + C_1 \, exp\left(-\frac{F_{ratio}}{C_2}\right)$

where:

$m_{ratio}$	=	Mass fraction of separated film mass
	=	Empirical constant (0.882)
	=	Empirical constant (-1.908)
	=	Empirical constant (1.264)

With the above model modification, the film separation begins when $F_{ratio}>1$ ; however, only the portion with $m_{ratio}$ separates while the rest stays attached.

Reference:

    Governing equations for the full film-separation model (tag:FLW):
        Friedrich, M. A., Lan, H., Wegener, J. L.,
        Drallmeier, J. A., & Armaly, B. F. (2008).
        A separation criterion with experimental
        validation for shear-driven films in separated flows.
        J. Fluids Eng. May 2008, 130(5): 051301.
        DOI:10.1115/1.2907405

    Governing equations for the partial film-separation model (tag:ZJD):
        Zhang, Y., Jia, M., Duan, H., Wang, P.,
        Wang, J., Liu, H., & Xie, M. (2018).
        Numerical and experimental study of spray impingement and liquid
        film separation during the spray/wall interaction at expanding corners.
        International Journal of Multiphase Flow, 107, 67-81.
        DOI:10.1016/j.ijmultiphaseflow.2018.05.016

Usage

Minimal example in boundary-condition files:

filmSeparationCoeffs
{
    // Mandatory entries
    model               Friedrich;
    rhop                <scalar>;

    // Optional entries
    separationType      <word>;
}

where the entries mean:

Property	Description	Type	Reqd	Deflt
`model`	Model name: Friedrich	word	yes	-
`rhop`	Primary-phase density	scalar	yes	-
`separationType`	Film separation type	word	no	full

Options for the separationType entry:

      full          | Full film separation (Friedrich et al., 2008)
      partial       | Partial film separation (Zhang et al., 2018)

Source files

Definition at line 237 of file FriedrichModel.H.

Constructor & Destructor Documentation

◆ FriedrichModel()

FriedrichModel	(	const regionModels::areaSurfaceFilmModels::liquidFilmBase &	film,
		const dictionary &	dict
	)

Construct from the base film model and dictionary.

Definition at line 480 of file FriedrichModel.C.

References Foam::abort(), dict, Foam::FatalIOError, FatalIOErrorInFunction, and Foam::mag().

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◆ ~FriedrichModel()

virtual ~FriedrichModel ( )

virtualdefault

Member Function Documentation

◆ TypeName()

TypeName ( "Friedrich" )

Runtime type information.

◆ separatedMassRatio()

tmp< scalarField > separatedMassRatio ( ) const

virtual

Calculate the mass ratio of film separation.

Implements filmSeparationModel.

Definition at line 521 of file FriedrichModel.C.

References tmp< T >::cref(), Foam::ensightOutput::debug, Foam::dimForce, Foam::exp(), forAll, filmSeparationModel::mesh(), tmp< T >::New(), GeometricField< Type, PatchField, GeoMesh >::primitiveFieldRef(), regIOobject::write(), and Foam::Zero.