nutkWallFunction

Table of Contents

Properties

  • The nutkWallFunction boundary condition provides a wall constraint on the turbulent viscosity, i.e. nut, based on the turbulent kinetic energy, i.e. k, for low- and high-Reynolds number turbulence models.
  • The nutkWallFunction 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

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

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

\[ y^+ = C_\mu^{1/4} y \frac{\sqrt{k}}{\nu_w} \]

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]
\( k \) = Turbulent kinetic energy [m2/s2]
\( f_{blend} \) = Wall-function blending operator between the viscous and inertial sublayer contributions

Usage

Example of the boundary condition specification: 

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

    // Optional (inherited) entries
    ...
}

where the entries mean:

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

The inherited entries are elaborated in:

Notes on entries

Further information

Tutorial

Source code