The open source CFD toolbox
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 [m2/s3]
omega     | Specific dissipation rate                 [1/s]


epsilon/omega   | Dissipation rate OR Spec. dissipation rate [m2/s3]/[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 ([69], 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:

# Further information

Tutorials

Source code

History

• Introduced in version v2006