Computes the Obukhov length field and associated friction velocity field. More...

Inheritance diagram for ObukhovLength:

Collaboration diagram for ObukhovLength:

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Public Member Functions
	TypeName ("ObukhovLength")

	ObukhovLength (const word &name, const Time &runTime, const dictionary &dict)

	ObukhovLength (const ObukhovLength &)=delete

void	operator= (const ObukhovLength &)=delete

virtual	~ObukhovLength ()=default

void	removeObukhovLength ()

virtual bool	read (const dictionary &dict)

virtual bool	execute ()

virtual bool	write ()

virtual void	updateMesh (const mapPolyMesh &mpm)

virtual void	movePoints (const polyMesh &m)

Public Member Functions inherited from fvMeshFunctionObject
	TypeName ("fvMeshFunctionObject")

	fvMeshFunctionObject (const word &name, const Time &runTime, const dictionary &dict)

	fvMeshFunctionObject (const word &name, const objectRegistry &obr, const dictionary &dict)

virtual	~fvMeshFunctionObject ()=default

Public Member Functions inherited from regionFunctionObject
	TypeName ("regionFunctionObject")

	regionFunctionObject (const word &name, const Time &runTime, const dictionary &dict)

	regionFunctionObject (const word &name, const objectRegistry &obr, const dictionary &dict)

virtual	~regionFunctionObject ()=default

template<class ObjectType >
const ObjectType *	lookupObjectPtr (const word &fieldName) const

template<class ObjectType >
ObjectType *	lookupObjectRefPtr (const word &fieldName) const

Public Member Functions inherited from stateFunctionObject
	stateFunctionObject (const word &name, const Time &runTime)

virtual	~stateFunctionObject ()=default

dictionary &	propertyDict ()

bool	foundProperty (const word &entryName) const

void	clearTrigger ()

label	getTrigger () const

bool	setTrigger (const label triggeri, bool increaseOnly=true)

bool	getDict (const word &entryName, dictionary &dict) const

bool	getObjectDict (const word &objectName, const word &entryName, dictionary &dict) const

template<class Type >
Type	getProperty (const word &entryName, const Type &defaultValue=Type(Zero)) const

template<class Type >
bool	getProperty (const word &entryName, Type &value) const

template<class Type >
void	setProperty (const word &entryName, const Type &value)

template<class Type >
Type	getObjectProperty (const word &objectName, const word &entryName, const Type &defaultValue=Type(Zero)) const

template<class Type >
bool	getObjectProperty (const word &objectName, const word &entryName, Type &value) const

template<class Type >
void	setObjectProperty (const word &objectName, const word &entryName, const Type &value)

template<class Type >
void	setResult (const word &entryName, const Type &value)

template<class Type >
void	setObjectResult (const word &objectName, const word &entryName, const Type &value)

template<class Type >
Type	getResult (const word &entryName, const Type &defaultValue=Type(Zero)) const

template<class Type >
Type	getObjectResult (const word &objectName, const word &entryName, const Type &defaultValue=Type(Zero)) const

template<class Type >
bool	getObjectResult (const word &objectName, const word &entryName, Type &value) const

word	resultType (const word &entryName) const

word	objectResultType (const word &objectName, const word &entryName) const

wordList	objectResultEntries () const

wordList	objectResultEntries (const word &objectName) const

void	writeResultEntries (Ostream &os) const

void	writeResultEntries (const word &objectName, Ostream &os) const

void	writeAllResultEntries (Ostream &os) const

Public Member Functions inherited from timeFunctionObject
	timeFunctionObject (const word &name, const Time &runTime)

virtual	~timeFunctionObject ()=default

const Time &	time () const

objectRegistry &	storedObjects ()

const objectRegistry &	storedObjects () const

Public Member Functions inherited from functionObject
	declareRunTimeSelectionTable (autoPtr, functionObject, dictionary,(const word &name, const Time &runTime, const dictionary &dict),(name, runTime, dict))

	functionObject (const word &name, const bool withNamePrefix=defaultUseNamePrefix)

autoPtr< functionObject >	clone () const

virtual	~functionObject ()=default

virtual const word &	type () const =0

const word &	name () const noexcept

bool	useNamePrefix () const noexcept

bool	useNamePrefix (bool on) noexcept

virtual bool	execute (const label subIndex)

virtual bool	end ()

virtual bool	adjustTimeStep ()

virtual bool	filesModified () const

Protected Member Functions
bool	calcOL ()

Protected Member Functions inherited from fvMeshFunctionObject
	fvMeshFunctionObject (const fvMeshFunctionObject &)=delete

void	operator= (const fvMeshFunctionObject &)=delete

Protected Member Functions inherited from regionFunctionObject
virtual const objectRegistry &	obr () const

template<class ObjectType >
bool	foundObject (const word &fieldName) const

template<class ObjectType >
const ObjectType *	cfindObject (const word &fieldName) const

template<class ObjectType >
const ObjectType *	findObject (const word &fieldName) const

template<class ObjectType >
ObjectType *	findObject (const word &fieldName)

template<class ObjectType >
ObjectType *	getObjectPtr (const word &fieldName) const

template<class ObjectType >
const ObjectType &	lookupObject (const word &fieldName) const

template<class ObjectType >
ObjectType &	lookupObjectRef (const word &fieldName) const

template<class ObjectType >
bool	store (word &fieldName, const tmp< ObjectType > &tfield, bool cacheable=false)

template<class ObjectType >
bool	storeInDb (const word &fieldName, const tmp< ObjectType > &tfield, const objectRegistry &obr)

bool	writeObject (const word &fieldName)

bool	clearObject (const word &fieldName)

void	clearObjects (const wordList &objNames)

	regionFunctionObject (const regionFunctionObject &)=delete

void	operator= (const regionFunctionObject &)=delete

Protected Member Functions inherited from stateFunctionObject
const functionObjects::properties &	stateDict () const

functionObjects::properties &	stateDict ()

	stateFunctionObject (const stateFunctionObject &)=delete

void	operator= (const stateFunctionObject &)=delete

Protected Member Functions inherited from timeFunctionObject
void	clearOutputObjects (const wordList &objNames)

	timeFunctionObject (const timeFunctionObject &)=delete

void	operator= (const timeFunctionObject &)=delete

Protected Member Functions inherited from functionObject
word	scopedName (const word &name) const

Protected Attributes
word	UName_

word	resultName1_

word	resultName2_

scalar	rhoRef_

scalar	kappa_

dimensionedScalar	beta_

const dimensionedVector	g_

Protected Attributes inherited from fvMeshFunctionObject
const fvMesh &	mesh_

Protected Attributes inherited from regionFunctionObject
word	subRegistryName_

const objectRegistry &	obr_

const objectRegistry *	obrPtr_

Protected Attributes inherited from timeFunctionObject
const Time &	time_

Additional Inherited Members
Static Public Member Functions inherited from functionObject
static autoPtr< functionObject >	New (const word &name, const Time &runTime, const dictionary &dict)

Public Attributes inherited from functionObject
bool	log

Static Public Attributes inherited from functionObject
static int	debug

static bool	postProcess

static bool	defaultUseNamePrefix

static word	outputPrefix

Detailed Description

Computes the Obukhov length field and associated friction velocity field.

When scaled by the ground-normal height, i.e. z, the Obukhov length becomes a dimensionless stability parameter, i.e. z/L, for atmospheric boundary layer modelling, expressing the relative roles of buoyancy and shear in the production and dissipation of turbulent kinetic energy.

$u^* = \sqrt{\max (\nu_t \sqrt{2 |\symm{\grad{u}}|^2}, VSMALL)}$

$L_o = - \frac{(u^*)^3}{sign(B) \kappa \max (|B|, VSMALL)}$

with

$B = \alpha_t \beta \frac{\grad{T} \cdot \vec{g}}{\rho}$

where

	=	Friction velocity [m/s]
$\nu_t$	=	Turbulent viscosity [m2/s]
	=	Velocity [m/s]
	=	Obukhov length [m]
	=	Buoyancy production term [m2/s3]
$\alpha_t$	=	Kinematic turbulent thermal conductivity [m2/s]/[kg/m/s]
$\rho$	=	Density of fluid [-]/[kg/m3]
$\beta$	=	Thermal expansion coefficient [1/K]
	=	Temperature [K]
	=	Gravitational acceleration [m/s2]
	=	A very small number to avoid floating point exceptions

References:

    Definition of the Obukhov length (tag:O):
        Obukhov, A. M. (1946).
        Turbulentnost'v temperaturnoj-neodnorodnoj atmosfere.
        Trudy Inst. Theor. Geofiz. AN SSSR, 1, 95-115.

        Obukhov, A. M. (1971).
        Turbulence in an atmosphere with a non-uniform temperature.
        Boundary-layer meteorology, 2(1), 7-29.
        DOI:10.1007/BF00718085

        Obukhov length. (2016).
        In American Meteorological Society - Glossary of meteorology.
        Retrieved Apr 1, 2020, from glossary.ametsoc.org/wiki/Obukhov_length

Required fields:

      U           | Velocity                                 [m/s]
      T           | Temperature                              [K]
      nut         | Turbulent viscosity                      [m2/s]
      alphat      | Kinematic turbulent thermal conductivity [m2/s]/[kg/m/s]
      g           | Gravitational acceleration               [m/s2]

Operand	Type	Location
`input`	-	-
`output` file	-	-
`output` field 1	volScalarField	$FOAM_CASE/<time>/<ObukhovLength>
`output` field 2	volScalarField	$FOAM_CASE/<time>/<Ustar>

Usage

Minimal example by using system/controlDict.functions:

ObukhovLength1
{
    // Mandatory entries (unmodifiable)
    type            ObukhovLength;
    libs            (fieldFunctionObjects);

    // Optional entries (runtime modifiable)
    U               U;
    result1         ObukhovLength;
    result2         Ustar;
    rhoRef          1.0;
    kappa           0.4;
    beta            3e-3;

    // Optional (inherited) entries
    ...
}

where the entries mean:

Property	Description	Type	Req'd	Dflt
`type`	Type name: ObukhovLength	word	yes	-
`libs`	Library name: fieldFunctionObjects	word	yes	-
`U`	Name of the velocity field	word	no	U
`result1`	Name of the output field for ObukhovLength	word	no	ObukhovLength
`result2`	Name of the output field for Ustar	word	no	Ustar
`rhoRef`	Reference density (to convert from kinematic to static pressure)	scalar	no	1.0
`kappa`	von Kármán constant	scalar	no	0.40
`beta`	Thermal expansion coefficient	scalar	no	3e-3

The inherited entries are elaborated in:

functionObject.H

Minimal example by using the postProcess utility:

        postProcess -func "ObukhovLength(<UField>)"

See also

Foam::functionObjects::fvMeshFunctionObject
ExtendedCodeGuide::atmosphericModels::functionObjects::ObukhovLength

Source files

Definition at line 293 of file ObukhovLength.H.

Constructor & Destructor Documentation

◆ ObukhovLength() [1/2]

ObukhovLength	(	const word &	name,
		const Time &	runTime,
		const dictionary &	dict
	)

Definition at line 137 of file ObukhovLength.C.

References dict, and Foam::read().

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◆ ObukhovLength() [2/2]

ObukhovLength ( const ObukhovLength & )

delete

◆ ~ObukhovLength()

virtual ~ObukhovLength ( )

virtualdefault

Member Function Documentation

◆ calcOL()

bool calcOL ( )

protected

Definition at line 44 of file ObukhovLength.C.

References B, ObukhovLength::beta_, dimensioned::dimensions(), Foam::dimLength, Foam::dimless, Foam::dimVelocity, objectRegistry::findObject(), ObukhovLength::g_, objectRegistry::getObjectPtr(), Foam::fvc::grad(), ObukhovLength::kappa_, objectRegistry::lookupObject(), Foam::mag(), Foam::magSqr(), Foam::max(), fvMeshFunctionObject::mesh_, Foam::min(), IOobject::NO_READ, IOobject::NO_WRITE, nut, Foam::pow3(), ObukhovLength::resultName1_, ObukhovLength::resultName2_, rho, rhoPtr, ObukhovLength::rhoRef_, Foam::sign(), Foam::sqr(), Foam::sqrt(), Foam::symm(), Foam::T(), fvMesh::time(), Time::timeName(), U, and ObukhovLength::UName_.

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◆ TypeName()

TypeName ( "ObukhovLength" )

◆ operator=()

void operator= ( const ObukhovLength & )

delete

◆ removeObukhovLength()

void removeObukhovLength ( )

Definition at line 234 of file ObukhovLength.C.

◆ read()

bool read ( const dictionary & dict )

virtual

Reimplemented from regionFunctionObject.

Definition at line 175 of file ObukhovLength.C.

References dict, Foam::constant::electromagnetic::e, and regionFunctionObject::read().

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◆ execute()

bool execute ( )

virtual

Implements functionObject.

Definition at line 201 of file ObukhovLength.C.

References Foam::endl(), Log, Foam::name(), Foam::nl, and Foam::type().

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◆ write()

bool write ( )

virtual

Implements functionObject.

Definition at line 215 of file ObukhovLength.C.

References Foam::endl(), Log, Foam::name(), IOobject::name(), Foam::nl, Foam::type(), Ostream::write(), and regIOobject::write().

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◆ updateMesh()

void updateMesh ( const mapPolyMesh & mpm )

virtual

Reimplemented from functionObject.

Definition at line 241 of file ObukhovLength.C.

References mapPolyMesh::mesh().

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◆ movePoints()

void movePoints ( const polyMesh & m )

virtual

Reimplemented from functionObject.

Definition at line 250 of file ObukhovLength.C.

Member Data Documentation

◆ UName_

word UName_

protected

Definition at line 302 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ resultName1_

word resultName1_

protected

Definition at line 305 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ resultName2_

word resultName2_

protected

Definition at line 308 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ rhoRef_

scalar rhoRef_

protected

Definition at line 311 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ kappa_

scalar kappa_

protected

Definition at line 314 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ beta_

dimensionedScalar beta_

protected

Definition at line 317 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

◆ g_

const dimensionedVector g_

protected

Definition at line 320 of file ObukhovLength.H.

Referenced by ObukhovLength::calcOL().

The documentation for this class was generated from the following files:

src/atmosphericModels/functionObjects/ObukhovLength/ObukhovLength.H
src/atmosphericModels/functionObjects/ObukhovLength/ObukhovLength.C

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ObukhovLength() [1/2]

◆ ObukhovLength() [2/2]

◆ ~ObukhovLength()

Member Function Documentation

◆ calcOL()

◆ TypeName()

◆ operator=()

◆ removeObukhovLength()

◆ read()

◆ execute()

◆ write()

◆ updateMesh()

◆ movePoints()

Member Data Documentation

◆ UName_

◆ resultName1_

◆ resultName2_

◆ rhoRef_

◆ kappa_

◆ beta_

◆ g_