atmPlantCanopyTurbSource

Table of Contents

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]

Required fields: 

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