Standard Spalart-Allmaras Model Reference

The Standard Spalart-Allmaras model allows you to compute the modified diffusivity $\tilde{ν}$ to provide closure to the Reynolds-Averaged Navier-Stokes equations.


Theory	See Theory Guide—Spalart Allmaras Model.
Provided By	[physics continuum] > Models > Rans Spalart-Allmaras Turbulence
Example Node Path	Continua > Physics 1 > Models > Standard Spalart-Allmaras
Requires	Space: Axisymmetric, Two Dimensional, or Three Dimensional Time: Steady, Implicit Unsteady, PISO Unsteady, or Harmonic Balance Material: Gas, Liquid, Multiphase, Multi-Component Gas, or Multi-Component Liquid Viscous Regime: Turbulent Turbulence: Reynolds-Averaged Navier-Stokes Reynolds-Averaged Turbulence: Spalart-Allmaras Turbulence
Properties	See Standard Spalart-Allmaras Properties.
Activates	Physics Models	Wall Distance: Wall Distance*
		Wall Treatment: All y+ Wall Treatment and Low y+ Wall Treatment
	Model Controls (child nodes)	Curvature Correction Parameters (optional, see Curvature Correction Option)
	Initial Conditions	See Standard Spalart-Allmaras Initial Conditions Reference.
	Boundary Inputs	See Standard Spalart-Allmaras Boundaries Reference.
	Region Inputs	See Standard Spalart-Allmaras Regions Reference.
	Solvers	Spalart-Allmaras Turbulence Spalart-Allmaras Turbulent Viscosity See Standard Spalart-Allmaras Solvers Reference.
	Monitors	Sa_nut (modified diffusivity)
	Field Functions	Effective Viscosity Modified Diffusivity SaTurbDeformation Turbulent Viscosity Turbulent Viscosity Ratio See Standard Spalart-Allmaras Field Functions Reference.

Standard Spalart-Allmaras Properties

Cb1

The coefficient

C_{b 1}

, Eqn. (1152) and Eqn. (1154).

Cb2

The coefficient

C_{b 2}

, Eqn. (1151) and Eqn. (1154).

Cnl1

The coefficient

C_{NL 1}

, Eqn. (1161).

Constitutive Option

Controls the type of constitutive relation used.

Linear: Selects the linear constitutive relation as implied by the Boussinesq approximation (see Eqn. (1147). Use this selection for most simulations.
QCR: Selects the quadratic constitutive relation (see Eqn. (1161)). This relation requires the coefficient Cnl1.

Convection

Controls the convection scheme.

1st-order: Selects the first-order upwind convection scheme.
2nd-order: Selects the second-order upwind convection scheme.

Cprod

The coefficient

C_{prod}

, Eqn. (1157).

Curvature Correction Option

Controls whether to apply a curvature correction, that accounts for effects of strong streamline curvature and rapid frame-rotation.

When On, a rotation function

f_{r 1}

is applied, that alters the turbulent kinetic energy production term according to local rotation and vorticity rates (see Eqn. (1152)). Only use this option when you have a stable solution, to improve the results.

Curvature Correction Parameters: Child node that provides the parameters Cr1, Cr2, and Cr3 to calculate $f_{r 1}$ using Eqn. (1286).

Cv1

The coefficient

C_{v 1}

, Eqn. (1158).

Cw2

The coefficient

C_{w 2}

, Eqn. (1154).

Cw3

The coefficient

C_{w 3}

, Eqn. (1154).

Deformation Option

Selects the modified or standard production term.

Modified: Selects the modified production term. This option is recommended for most simulations. See Eqn. (1157).
Original: Selects the standard production term. This option allows comparison with results from other CFD codes that lack the modified production term. See Eqn. (1156).

Kappa

The von Karman constant

κ

, Eqn. (1154) and Eqn. (1155).

Secondary Gradients

Neglect or include the boundary secondary gradients for diffusion and/or the interior secondary gradients at mesh faces.

On: Include both secondary gradients.
Off: Exclude both secondary gradients.
Interior Only: Include the interior secondary gradients only.
Boundaries Only: Include the boundary secondary gradients only.

Sigma

The coefficient

σ_{\bar{ν}}

,Eqn. (1149).