nutUWallFunction

- 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]

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