Standard Spalart-Allmaras Regions Reference

This section details the conditions that are required for each region type that is supported by the Standard Spalart-Allmaras turbulence model. In addition, information is provided about the values for each region type.

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

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

Fluid Region

Turbulence Source Option

Controls whether you want to use a turbulence source term.

Turbulence Source Option	Corresponding Value Nodes
Deactivated	None.
Activated	Modified Diffusivity Source Scalar profile value to specify a turbulence source for $\tilde{ν}$ directly.

Porous Region

Turbulence Specification

Controls how you define the turbulence profile.

The Spalart-Allmaras model requires the modified turbulent diffusivity $\tilde{ν}$ . You can enter the corresponding value directly or have it derived from other turbulence quantities.

Method	Corresponding Value Nodes
Modified Turbulent Diffusivity	Modified Diffusivity Scalar profile value to specify $\tilde{ν}$ directly.
Intensity + Length Scale Calculation of $\tilde{ν}$ from a specified coefficient $C_{μ}$ , turbulence intensity $I$ , and length scale $l$ using Eqn. (1354). Do not use this method if the velocity field is initialized to zero.	Cmu coefficient Scalar value to specify $C_{μ}$ . Turbulence Intensity Scalar profile value to specify $I$ . Turbulent Length Scale Scalar profile value to specify $l$ .
Turbulent Viscosity Ratio Calculation of $\tilde{ν}$ from a specified turbulent viscosity ratio $μ_{t} / μ$ using Eqn. (1355).	Turbulent Viscosity Ratio Scalar profile value to specify the ratio of turbulent to laminar viscosity $μ_{t} / μ$ .

Method

Corresponding Value Nodes

Modified Turbulent Diffusivity

Modified Diffusivity: Scalar profile value to specify $\tilde{ν}$ directly.

Intensity + Length Scale

Calculation of $\tilde{ν}$ from a specified coefficient $C_{μ}$ , turbulence intensity $I$ , and length scale $l$ using Eqn. (1354).

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

Cmu coefficient: Scalar value to specify $C_{μ}$ .
Turbulence Intensity: Scalar profile value to specify $I$ .
Turbulent Length Scale: Scalar profile value to specify $l$ .

Turbulent Viscosity Ratio

Calculation of $\tilde{ν}$ from a specified turbulent viscosity ratio $μ_{t} / μ$ using Eqn. (1355).

Turbulent Viscosity Ratio: Scalar profile value to specify the ratio of turbulent to laminar viscosity $μ_{t} / μ$ .