K-Epsilon Boundaries Reference

This section details the conditions that are required for each boundary type that is supported by the K-Epsilon turbulence model. In addition, information is provided about the values for each boundary type.

Boundary conditions and values are elected by the boundary type, and/or by methods selected in corresponding nodes in the Conditions node.

Note	Boundary types that do not require setting any conditions or values are not listed.

Flow Boundaries

The following boundary conditions and values are equal to all boundaries of type:

Free Stream
Mass Flow Inlet
Pressure Outlet
Stagnation Inlet
Velocity Inlet

Turbulence Specification

Controls how you define the turbulence profile at flow boundaries.

The K-Epsilon model requires the turbulent kinetic energy $k$ and the turbulent dissipation rate $ε$ . You can enter the corresponding values directly or have them derived from other turbulence quantities.

Method	Corresponding Value Nodes
K + Epsilon	Turbulent Kinetic Energy Scalar profile value to specify $k$ directly. Turbulent Dissipation Rate Scalar profile value to specify $ε$ directly. Reduced Stress Function (EB KE, EBL KE) Scalar profile value to specify the reduced stress function $φ$ directly. The EB KE model solves an additional transport equation for this quantity.
Intensity + Length Scale Calculation of $k$ and $ε$ from a specified turbulence intensity $I$ and length scale $l$ using Eqn. (1356) and Eqn. (1358). Do not use this method if the velocity field is initialized to zero.	Turbulence Intensity Scalar profile value to specify $I$ . Turbulent Length Scale Scalar profile value to specify $l$ . Reduced Stress Function (EB KE, EBL KE) As for K+Epsilon.
Intensity + Viscosity Ratio Calculation of $k$ and $ε$ from a specified turbulence intensity $I$ and viscosity ratio $μ_{t} / μ$ using Eqn. (1357) and Eqn. (1359). Do not use this method if the velocity field is initialized to zero.	Turbulence Intensity As for Intensity + Length Scale. Turbulent Viscosity Ratio Scalar profile value to specify the ratio of turbulent to laminar viscosity $μ_{t} / μ$ . Reduced Stress Function (EB KE, EBL KE) As for K+Epsilon.

Method

Corresponding Value Nodes

K + Epsilon

Turbulent Kinetic Energy: Scalar profile value to specify $k$ directly.
Turbulent Dissipation Rate: Scalar profile value to specify $ε$ directly.
Reduced Stress Function (EB KE, EBL KE): Scalar profile value to specify the reduced stress function $φ$ directly. The EB KE model solves an additional transport equation for this quantity.

Intensity + Length Scale

Calculation of $k$ and $ε$ from a specified turbulence intensity $I$ and length scale $l$ using Eqn. (1356) and Eqn. (1358).

Do not use this method if the velocity field is initialized to zero.

Turbulence Intensity: Scalar profile value to specify $I$ .
Turbulent Length Scale: Scalar profile value to specify $l$ .
Reduced Stress Function (EB KE, EBL KE): As for K+Epsilon.

Intensity + Viscosity Ratio

Calculation of $k$ and $ε$ from a specified turbulence intensity $I$ and viscosity ratio $μ_{t} / μ$ using Eqn. (1357) and Eqn. (1359).

Do not use this method if the velocity field is initialized to zero.

Turbulence Intensity: As for Intensity + Length Scale.
Turbulent Viscosity Ratio: Scalar profile value to specify the ratio of turbulent to laminar viscosity $μ_{t} / μ$ .
Reduced Stress Function (EB KE, EBL KE): As for K+Epsilon.