atmNutkWallFunction
boundary condition 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.atmNutkWallFunction
condition inherits the traits of the nutkWallFunction
boundary condition.Required fields:
nut | Turbulent viscosity [m2/s] k | Turbulent kinetic energy [m2/s2]
The boundary condition expression is (based on ([24], Eq. 5)):
\[ \nu_{t_w} = \nu_w \left( \frac{y^+ \kappa}{\ln \left( max (E^\prime, 1 + 10^{-4}) \right) } - 1 \right) \]
with
\[ u^* = C_\mu^{1/4} \sqrt{k} \]
\[ y^+ = \frac{u^* y}{\nu_w} \]
\[ E^\prime = \frac{y + z_0}{z_0} \]
where
\( \nu_{t_w} \) | = | Turbulent viscosity [m2/s] |
\( \nu_w \) | = | Kinematic viscosity of fluid near wall [m2/s] |
\( y^+ \) | = | Wall-normal distance in wall units [-] |
\( \kappa \) | = | von Kármán constant [-] |
\( u^* \) | = | Friction velocity [m/s] |
\( C_\mu \) | = | Empirical model constant [-] |
\( k \) | = | Turbulent kinetic energy [m2/s2] |
\( z_0 \) | = | Surface roughness length [m] |
Example of the boundary condition specification:
<patchName> { // Mandatory entries (unmodifiable) type atmNutkWallFunction; // Mandatory entries (runtime modifiable) z0 uniform 0.001; // Optional entries (unmodifiable) boundNut false; // Optional (inherited) entries Cmu 0.09; kappa 0.41; }
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: atmNutkWallFunction | word | yes | - |
z0 | Surface roughness length [m] | PatchFunction1<scalar> | yes | - |
boundNut | Flag: zero-bound nut near wall | bool | no | false |
Cmu | Empirical model constant | scalar | no | 0.09 |
kappa | von Kármán constant | scalar | no | 0.41 |
The inherited entries are elaborated in:
Tutorial:
Source code
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