SA working-variable bounds after update

After each explicit/implicit update, the SA working variable is limited.

Non-negativity

Negative values are replaced by a fallback (typically freestream \(\tilde\nu\)):

\[\begin{split}\tilde\nu \leftarrow \begin{cases} \tilde\nu_\infty & \tilde\nu < 0 \\ \tilde\nu & \text{otherwise} \end{cases}\end{split}\]

Eddy-viscosity ratio cap

With \(f_{v1}(\chi)\) evaluated at the current state:

\[\tilde\nu_{\max} = r_{\max}\,\frac{\mu_l}{\rho f_{v1}}\]

References

• Spalart–Allmaras implementation practice; NASA TMR.

• See sa_eddy_viscosity.rst and verification_layers.rst.

Pure APIs: SaWorkingVariableUpperBound, SaNonNegativeWorkingVariable.