atmPlantCanopyUSource

Properties

• The atmPlantCanopyUSource applies sources on velocity, i.e. U, to incorporate effects of plant canopy for atmospheric boundary layer modelling.
• The atmPlantCanopyUSource can be applied on any RAS turbulence model.
• The atmPlantCanopyUSource inherits the traits of the fvOption, and cellSetOption.

Corrections applied to:

U : Velocity [m/s]

Required fields:

U : Velocity [m/s]

plantCd : Plant canopy drag coefficient [-]

leafAreaDensity : Leaf area density [1/m]

Model equations

The model expression (65, Eq. 42):

$$S_p -= \alpha \rho \left( C_d {LAD} |\u_o| \right) \u$$

where

$f_M$ : fvMatrix of the velocity field

$C_d$ : Plant canopy drag coefficient [-]

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

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

$\alpha$ : 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:

atmPlantCanopyUSource1
{
    // Mandatory entries (unmodifiable)
    type                  atmPlantCanopyUSource;

    atmPlantCanopyUSourceCoeffs
    {
        // 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: atmPlantCanopyUSource	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

• atmPlantCanopyUSource

History: Introduced in version v2006