atmPlantCanopyTurbSource

Properties

• The atmPlantCanopyTurbSource applies sources on either epsilon or omega to incorporate effects of plant canopy for atmospheric boundary layer modelling.
• The atmPlantCanopyTurbSource can be applied on epsilon or omega based RAS turbulence models.
• The atmPlantCanopyTurbSource inherits the traits of the fvOption, and cellSetOption.

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:

epsilon/omega : Dissipation rate OR Spec. dissipation rate [m$^2$/s$^3$]/[1/s]

plantCd : Plant canopy drag coefficient [-]

leafAreaDensity : Leaf area density [1/m]

Model equations

Turbulent kinetic energy dissipation rate

The model expression for epsilon:

$$S_p -= \alpha \rho \left( C_1 - C_2 \right) C_{canopy} \epsilon$$

with (65, Eq. 42):

$$C_{canopy} = 12.0 \sqrt{C_\mu} C_d {LAD} |\u_o|$$

Specific dissipation rate

The model expression for omega:

$$S_p -= \alpha \rho \left( \gamma - \beta \right) C_{canopy} \omega$$

Where:

$S_p$ : Source term without boundary conditions

$C_1$ : Model constant (epsilon-based models) [-]

$C_2$ : Model constant (epsilon-based models) [-]

$C_\mu$ : Empirical model constant [-]

$\beta$ : Model constant (omega-based models) [-]

$\gamma$ : Model constant (omega-based models) [-]

$\epsilon$ : Turbulent kinetic energy dissipation rate (Current iteration) [m2/s3]

$\omega$ : Specific dissipation rate (Current iteration) [1/s]

$C_d$ : Plant canopy drag coefficient [-]

${LAD}$ : Leaf area density [1/m]

$\u_o$ : Previous-iteration velocity field [m/s]

$C_{canopy}$ : Plant canopy term

$\alpha$ : 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:

atmPlantCanopyTurbSource1
{
    // Mandatory entries (unmodifiable)
    type                  atmPlantCanopyTurbSource;

    atmPlantCanopyTurbSourceCoeffs
    {
        // Mandatory (inherited) entries (unmodifiable)
        selectionMode    all;

        // Optional entries (unmodifiable)
        rho             rho;
    }

    // Optional (inherited) entries
    ...
}

where the entries mean:

Property	Description	Type	Required	Default
type	Type name: atmPlantCanopyTurbSource	word	yes	-
rho	Name of density field	word	no	rho

The inherited entries are elaborated in:

• fvOption
  • cellSetOption

Further information

Tutorials

• atmFlatTerrain
• atmForestStability

Source code

• atmPlantCanopyTurbSource

History: Introduced in version v2006