Properties

The nutUWallFunction boundary condition provides a wall constraint on the turbulent viscosity, i.e. nut, based on velocity, i.e. U, for low- and high-Reynolds number turbulence models.
The nutUWallFunction condition inherits the traits of the nutWallFunction boundary condition.

Required fields:

nut  | Turbulent viscosity         [m2/s]

Model equations

The model expressions:

\[ \nu_t = f_{blend}(\nu_{t_{vis}}, \nu_{t_{log}}) \]

with

\[ \nu_{t_{vis}} = 0 \]

\[ \nu_{t_{log}} = \nu_w \left( \frac{y^+ \kappa}{\ln(E y^+)} - 1 \right) \]

\[ y^+ = \max \left( 0, \frac{\kappa_{Re} y^+_{lam}}{1 + \ln(E y^+_{lam}) } \right) \]

\[ \kappa_{Re} = \frac{\kappa u_p y}{\nu_w} \]

where

$ \nu_t $	=	Turbulent viscosity [m2/s]
$ \nu_{t_{vis}} $	=	$\nu_t$ computed by the viscous sublayer assumptions [m2/s]
$ \nu_{t_{log}} $	=	$\nu_t$ computed by the inertial sublayer assumptions [m2/s]
$ \nu_w $	=	Kinematic viscosity of fluid near wall [m2/s]
$ y^+ $	=	Estimated wall-normal height of the cell centre in wall units
$ \kappa $	=	von Kármán constant [-]
$ E $	=	Wall roughness parameter [-]
$ C_\mu $	=	Empirical model constant [-]
$ y $	=	Wall-normal height [m]
$ f_{blend} $	=	Wall-function blending operator between the viscous and inertial sublayer contributions

Example of the boundary condition specification:

<patchName>
{
    // Mandatory entries (unmodifiable)
    type            nutUWallFunction;

    // Optional (inherited) entries
    ...
}

where the entries mean:

Property	Description	Type	Required	Default
type	Type name: nutUWallFunction	word	yes	-

The inherited entries are elaborated in:

Suffers from non-exact restart since correctNut() (called through turbulence->validate) returns a slightly different value every time it is called. See nutUSpaldingWallFunction.
Please refer to Foam::nutUWallFunctionFvPatchScalarField::calcYPlus function for the details on how $y^+$ is computed.
See nutWallFunction for the wall function blending treatments.

Tutorial

Source code

\( \nu_t \)	=	Turbulent viscosity [m2/s]
\( \nu_{t_{vis}} \)	=	\(\nu_t\) computed by the viscous sublayer assumptions [m2/s]
\( \nu_{t_{log}} \)	=	\(\nu_t\) computed by the inertial sublayer assumptions [m2/s]
\( \nu_w \)	=	Kinematic viscosity of fluid near wall [m2/s]
\( y^+ \)	=	Estimated wall-normal height of the cell centre in wall units
\( \kappa \)	=	von Kármán constant [-]
\( E \)	=	Wall roughness parameter [-]
\( C_\mu \)	=	Empirical model constant [-]
\( y \)	=	Wall-normal height [m]
\( f_{blend} \)	=	Wall-function blending operator between the viscous and inertial sublayer contributions