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12.19.17 Customizing the Turbulent Prandtl Numbers

If you are using the standard or realizable $k$- $\epsilon$ model or the standard $k$- $\omega$ model, a user-defined function can be used to customize the turbulent Prandtl numbers. This option will allow you to calculate $\sigma_k$ and either $\sigma_{\epsilon}$ or $\sigma_{\omega}$ (depending on if you have enabled the appropriate $k$- $\epsilon$ or $k$- $\omega$ model) by using a UDF. You will also be able to calculate the value of the energy Prandtl number (Pr $_t$ in Equation  12.4-23) and the Prandtl number at the wall (Pr $_t$ in Equation  12.10-5) in this way. See the separate UDF Manual for information about user-defined functions.

In the Viscous Model panel, under User-Defined Functions, select the appropriate user-defined function from the drop-down lists under Prandtl Numbers. Options include: TKE Prandtl Number, TDR Prandtl Number ( $k$- $\epsilon$ models only), SDR Prandtl Number ( $k$- $\omega$ model only), Energy Prandtl Number, and Wall Prandtl Number.

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