The open source CFD toolbox
atmBoundaryLayerInletEpsilon

# Properties

• The atmBoundaryLayerInletEpsilon boundary condition provides a generalised log-law type ground-normal inlet boundary condition for the turbulent kinetic energy dissipation rate, i.e. epsilon, for homogeneous, two-dimensional, dry-air, equilibrium and neutral atmospheric boundary layer modelling.
• The atmBoundaryLayerInletEpsilon boundary condition inherits the traits of the atmBoundaryLayer, and inletOutlet.

# Model equations

The ground-normal turbulent kinetic energy dissipation rate profile expression, i.e. epsilon (([99], Eq. 22), ([63], Eq. 8), ([24], Eq. 7 when C1=0 and C2=1)):

$\epsilon = \frac{(u^*)^3}{\kappa (z - d + z_0)} \sqrt{C_1 \ln \left( \frac{z - d + z_0}{z_0} \right) + C_2}$

where

 $$\epsilon$$ = Ground-normal turbulent kinetic energy dissipation rate profile [m2/s3] $$u^*$$ = Friction velocity [m/s] $$\kappa$$ = von Kármán constant [-] $$z$$ = Ground-normal coordinate component [m] $$z_0$$ = Aerodynamic roughness length [m] $$d$$ = Ground-normal displacement height [m] $$C_1$$ = Curve-fitting coefficient for [99] profiles [-] $$C_2$$ = Curve-fitting coefficient for [99] profiles [-]

# Usage

Example of the boundary condition specification:

inlet
{
// Mandatory entries (unmodifiable)
type            atmBoundaryLayerInletEpsilon;

// Mandatory (inherited) entries (runtime modifiable)
flowDir         (1 0 0);
zDir            (0 0 1);
Uref            10.0;
Zref            0.0;
z0              uniform 0.1;
d               uniform 0.0;

// Optional (inherited) entries (unmodifiable)
kappa           0.41;
Cmu             0.09;
initABL         true;
phi             phi;
C1              0.0;
C2              1.0;

// Conditional mandatory (inherited) entries (runtime modifiable)
value           uniform 0;    // when initABL=false
}


where the entries mean:

Property Description Type Required Default
type Type name: atmBoundaryLayerInletEpsilon word yes -

The inherited entries are elaborated in:

# Further information

Tutorial:

Source code:

History

• Introduced in version 1.7.0