6.2.20 Hooking DEFINE_SOX_RATE UDFs

After you have compiled (Chapter  5) your DEFINE_SOX_RATE UDF in ANSYS FLUENT, the function name you supplied in the DEFINE macro argument (e.g., user_sox::libudf) will become visible and selectable for the SOx Rate drop-down list in the SOx Model dialog box (Figure  6.2.28).

Models SOx Edit...

Figure 6.2.28: The SOx Model Dialog Box

By default, the custom SOx rate of your UDF is added to the rate calculated internally by ANSYS FLUENT. The UDF rate will be added to the forward rate if it is assigned to the POLLUT_FRATE macro, or the reverse rate if it is assigned to the POLLUT_RRATE macro. If you would rather entirely replace the internally calculated SOx rate with your custom rate, select Replace FLUENT Rate in the UDF Rate group box and click Apply.

Unless specifically defined in your SOx rate UDF, data and parameter settings will be derived from the settings in the SOx Model dialog box. Therefore, it is good practice to make the appropriate settings in the SOx Model dialog box, even though you may use a UDF to replace the default rates with user-specified rates. There is no computational penalty for doing this because the default rate calculations will be ignored when Replace FLUENT Rate is selected.

To specify a custom maximum limit ( $T_{\rm max}$) for the integration of the temperature PDF for each cell, you must first select the UDF name (e.g., user_sox::libudf) from the SOx Rate drop-down list, as described previously. Then, select either temperature or temperature/species from the PDF Mode drop-down list in the Turbulence Interaction Mode group box. Finally, select user-defined from the Tmax Option drop-down list and click Apply.

See Section  2.3.20 for details about defining DEFINE_SOX_RATE functions.