turbulentMixingLengthDissipationRateInlet

Description

The turbulentMixingLengthDissipationRateInlet is a boundary condition that calculates turbulent kinetic energy dissipation rate, i.e. epsilon, based on a specified mixing length. The patch values are calculated using:

$$\epsilon_p = \frac{C_{\mu}^{0.75} k^{1.5}}{L}$$

where:

Property	Description
$\epsilon_p$	Patch epsilon values [m^2/s^3]
$C_\mu$	Empirical model constant retrieved from turbulence model
$k$	Turbulent kinetic energy [m^2/s^2]
$L$	Mixing length scale [m]

Usage

The condition requires entries in both the boundary and field files.

Boundary file

<patchName>
{
    type            patch;
    ...
}

Field file

<patchName>
{
    // Mandatory entries
    type            turbulentMixingLengthDissipationRateInlet;
    mixingLength    <scalar>;

    // Optional entries
    Cmu             <scalar>;
    k               <word>;
    phi             <word>;

    // Inherited entries
    ...
}

where:

Property	Description	Type	Required	Default
type	Type name: turbulentMixingLengthDissipationRateInlet	word	yes	-
mixingLength	Mixing length scale [m]	scalar	yes	-
Cmu	Empirical model constant	scalar	no	0.09
phi	Name of flux field	word	no	phi
k	Name of turbulent kinetic energy field	word	no	k

The inherited entries are elaborated in:

• inletOutletFvPatchFields.H

• The boundary condition is derived from inletOutlet condition. Therefore, in the event of reverse flow, a zero-gradient condition is applied.
• The order of precedence to input the empirical model constant Cmu is: turbulence model, boundary condition dictionary, and default value=0.09.
• The empirical model constant Cmu is not a spatiotemporal variant field. Therefore, the use of the boundary condition may not be fully consistent with the turbulence models where Cmu is a variant field, such as realizableKE closure model in this respect. Nevertheless, workflow observations suggest that the matter poses no importance.

Further information

Tutorial:

• TJunctionAverage

Source code:

• turbulentMixingLengthDissipationRateInlet

API:

• Foam::turbulentMixingLengthDissipationRateInletFvPatchScalarField

History: Introduced in version 2.2.2