atmNutkWallFunction

Description

The atmNutkWallFunction is a boundary condition that provides a wall constraint on the turbulent viscosity (i.e. nut) based on the turbulent kinetic energy (i.e. k) for atmospheric boundary layer modelling. It is designed to be used in conjunction with the atmBoundaryLayerInletVelocity boundary condition.

The governing equation of the boundary condition:

$$u = \frac{u^*}{\kappa} ln \left(\frac{z + z_0}{z_0}\right)$$

where:

Property	Description
$u^*$	Friction velocity
$\kappa$	von Karman constant
$z_0$	Surface roughness length [m]
$z$	Ground-normal coordinate

References

• Theoretical expressions (tag:HW):

Hargreaves, D. M., & Wright, N. G. (2007).
On the use of the k–ε model in commercial CFD software to model
the neutral atmospheric boundary layer.
J. of wind engineering and industrial aerodynamics, 95(5), 355-369.
DOI:10.1016/j.jweia.2006.08.002

Usage

The condition requires entries in both the boundary and field files.

Boundary file

<patchName>
{
    type            patch;
    ...
}

Field file

<patchName>
{
    // Mandatory entries
    type            atmNutkWallFunction;
    z0              <PatchFunction1<scalar>>;

    // Optional entries
    boundNut        <bool>;

    // Inherited entries
    ...
}

where:

Property	Description	Type	Required	Default
type	Type name: atmNutkWallFunction	word	yes	-
z0	Surface roughness length [m]	PatchFunction1<scalar>	yes	-
boundNut	Flag to zero-bound nut near wall	bool	no	false

The inherited entries are elaborated in:

• nutkWallFunctionFvPatchScalarField.H
• PatchFunction1.H

Further information

Tutorial:

• turbineSiting

Source code:

• atmNutkWallFunction

API:

• Foam::atmNutkWallFunctionFvPatchScalarField

History: Introduced in version v2006