Properties🔗
- The
atmLengthScaleTurbSource
applies sources on eitherepsilon
oromega
to correct mixing-length scale estimations for atmospheric boundary layer modelling. - The
atmLengthScaleTurbSource
can be applied onepsilon
oromega
based RAS turbulence models. - The
atmLengthScaleTurbSource
inherits the traits of the fvOption, andcellSetOption
.
Corrections applied to either of the below, if exist:
epsilon
- Turbulent kinetic energy dissipation rate [m\(^2\)/s\(^3\)]
omega
- Specific dissipation rate [1/s]
Required fields, either of the below:
epsilon
- Turbulent kinetic energy dissipation rate [m\(^2\)/s\(^3\)]
omega
- Specific dissipation rate [1/s]
Model equations🔗
Turbulent kinetic energy dissipation rate🔗
The model expression for epsilon
:
with ([4], Eq. 16 wherein the
exponentiation n
is not present. n
is an ad-hoc implementation):
Mixing-length scale estimation ([59], Eq. 10.37 & p. 374):
\[L = C_\mu^{3/4} \frac{k_o^{3/2}}{\epsilon_o}\]Specific dissipation rate🔗
The model expression for omega
:
with ([33], Eq. 3.34):
\[\gamma^* = \left( \gamma - \beta \right) \left( \frac{L}{L_{max}} \right)^n\]Mixing-length scale estimation ([33], Eq. 3.20):
\[L = \frac{\sqrt{k}}{C_\mu^{1/4} \omega_o}\]Where:
- \(S_p\)
- Source term without boundary conditions
- \(\epsilon_o\)
- Previous-iteration epsilon [m2/s3]
- \(\omega_o\)
- Previous-iteration omega [1/s]
- \(k_o\)
- Previous-iteration k [m2/s2]
- \(G_o\)
- Previous-iteration k-production contribution [m2/s3]
- \(C_1\)
- Model constant (epsilon-based models) [-]
- \(C_2\)
- Model constant (epsilon-based models) [-]
- \(C_1^*\)
- Modified model constant field (epsilon-based models) [-]
- \(C_\mu\)
- Empirical model constant [-]
- \(\gamma\)
- Model constant (omega-based models) [-]
- \(\beta\)
- Model constant (omega-based models) [-]
- \(\gamma^*\)
- Modified model constant field (omega-based models) [-]
- \(\nu\)
- Kinematic viscosity of fluid [m2/s]
- \(L\)
- Mixing-length scale [m]
- \(L_{max}\)
- Maximum mixing-length scale [m]
- \(\alpha\)
- Phase fraction in multiphase computations, otherwise equals to 1
- \(\rho\)
- Fluid density in compressible computations, otherwise equals to 1
Usage🔗
Example of the fvOptions specification using constant/fvOptions
file:
atmLengthScaleTurbSource1
{
// Mandatory entries (unmodifiable)
type atmLengthScaleTurbSource;
atmLengthScaleTurbSourceCoeffs
{
// Mandatory (inherited) entries (unmodifiable)
selectionMode all;
// Optional entries (unmodifiable)
rho rho;
Lmax 41.575;
n 3.0;
}
// Optional (inherited) entries
...
}
where the entries mean:
Property | Description | Type | Required | Default |
---|---|---|---|---|
type | Type name: atmLengthScaleTurbSource | word | yes | - |
rho | Name of density field | word | no | rho |
Lmax | Maximum mixing-length scale | scalar | no | 41.575 |
n | Mixing-length scale exponent | scalar | no | 3.0 |
The inherited entries are elaborated in:
-
fvOption
cellSetOption
Further information🔗
Tutorials
- $FOAM_TUTORIALS/verificationAndValidation/atmosphericModels/atmFlatTerrain
- $FOAM_TUTORIALS/verificationAndValidation/atmosphericModels/atmForestStability
Source code
History:
- Introduced in version v2006