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:

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


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]


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

Boundary file

    type            patch;

Field file

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

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

    // Inherited entries


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


Source code:



  • Introduced in version 2.2.2