Standard Spalart-Allmaras Boundaries Reference

This section details the conditions that are required for each boundary type that is supported by the Standard Spalart-Allmaras 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 flow boundaries of type:

Free Stream
Mass Flow Inlet
Pressure Outlet
Stagnation Inlet
Velocity Inlet

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 $μ_{t} / μ$ .