nutUBlendedWallFunction

Description

The nutUBlendedWallFunction is boundary condition that provides a wall function for the turbulent viscosity (i.e. nut) based on velocity (i.e. U) using a binomial-function wall-function blending method between the viscous and inertial sublayer predictions of \c nut for low- and high-Reynolds number applications.

$$u_\tau = (u_{\tau,vis}^n + u_{\tau,log}^n)^{1/n}$$

where:

Property	Description
$u_\tau$	Friction velocity
$u_{\tau,vis}$	Friction velocity in the viscous sublayer
$u_{\tau,log}$	Friction velocity in the inertial sublayer

References

• See the section that describes 'automatic wall treatment':

Menter, F., Ferreira, J. C., Esch, T., Konno, B. (2003).
The SST turbulence model with improved wall treatment
for heat transfer predictions in gas turbines.
In Proceedings of the International Gas Turbine Congress.
November, 2003. Tokyo, Japan. pp. 2-7.

Usage

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

Boundary file

<patchName>
{
    type            wall;
    ...
}

Field file

<patchName>
{
    // Mandatory entries
    type            nutUBlendedWallFunction;

    // Optional entries
    n               4.0;

    // Inherited entries
    ...
}

where:

Property	Description	Type	Required	Default
type	Type name: nutUBlendedWallFunction	word	yes	-
n	Blending type	scalar	no	4.0

The inherited entries are elaborated in:

• nutWallFunctionFvPatchScalarField.H

• The full 'automatic wall treatment' description also requires use of the \link omegaWallFunctionFvPatchScalarField.H with the \c blending option binomial or with the deprecated blended flag set to on.
• Suffers from non-exact restart since correctNut() (called through turbulence->validate) returns a slightly different value every time it is called. See nutUSpaldingWallFunctionFvPatchScalarField.C.

Further information

Tutorial:

• backwardFacingStep2D

Source code:

• nutUBlendedWallFunction

API:

• Foam::nutUBlendedWallFunctionFvPatchScalarField

History: Introduced in version 2.4.0