12.13.17 Customizing the Turbulent Viscosity

If you are using the Spalart-Allmaras, $k$- $\epsilon$, $k$- $\omega$, DES, or LES models, a user-defined function can be used to customize the turbulent viscosity. This option will enable you to modify $\mu_t$ in the case of the Spalart-Allmaras, $k$- $\epsilon$, and $k$- $\omega$ models, and incorporate completely new subgrid models in the case of the LES model. More information about user-defined functions can be found in the separate UDF Manual.

In the Viscous Model dialog box, under User-Defined Functions, select the appropriate user-defined function in the Turbulent Viscosity drop-down list. For the LES model, select the appropriate UDF in the Subgrid-Scale Turbulent Viscosity drop-down list.