Uniform Sources/Sinks

Note

Refer to Physical Processes for general information about processes and their implementation.

The uniform sources add a constant value $S$ to the rate of change of a quantity $q$. This contribution is uniform in space and therefore only affects the $(0, 0)$ wavenumber pairs. If $S$ is negative, the term acts as a sink rather than a source.

Source/Sink with Constant Strength

Source term for a scalar quantity $q$ with source strength $S$ that is constant in space and time, i.e.

\[\frac{∂q}{∂t} = … + S \,.\]

The process is discretized with

\[f_i(\hat{q}^{00ζ}) = S \,.\]

BoundaryLayerDynamics.Processes.ConstantSource — Type

ConstantSource(field, strength = 1)

Source term for a scalar quantity $q$ with source strength $S$ that is constant in space and time.

Arguments

field::Symbol: The name of the quantity $q$.
strength::Real: The source strength $S$.

source

Source/Sink to Maintain Constant Mean

BoundaryLayerDynamics.Processes.ConstantMean — Type

ConstantMean(field, mean_value = 1)

Source term for a scalar quantity $q$ with a source strength that is constant in space but dynamically adjusted in time to maintain a constant mean value $Q$ for $q$.

Arguments

field::Symbol: The name of the quantity $q$.
mean_value::Real: The mean value $Q$ that is maintained.

source

Note

ConstantMean is currently only implemented for $ζ_C$-nodes.

Contributions to Budget Equations

Contribution to the instantaneous momentum equation:

\[\frac{\partial}{\partial t} u_i = … + f_i\]

Contribution to the mean momentum equation:

\[\frac{\partial}{\partial t} \overline{u_i} = … + \overline{f_i}\]

Contribution to the turbulent momentum equation:

\[\frac{\partial}{\partial t} u_i^\prime = … + f_i^\prime\]

Contribution to the mean kinetic energy equation:

\[\frac{\partial}{\partial t} \frac{\overline{u_i}^2}{2} = … + \overline{u_i} \overline{f_i}\]

Contribution to the turbulent kinetic energy equation:

\[\frac{\partial}{\partial t} \frac{\overline{u_i^\prime u_i^\prime}}{2} = … + \overline{u_i^\prime f_i^\prime}\]

Note

For the ConstantSource process, $\overline{f_i}=S$ and $f_i^\prime=0$, but for the ConstantMean process this may depend on the exact definition of the averaging operation.