Many pollutant species, such as NOx, are slowly forming relative to the major combustion products, and require a finite-rate chemistry calculation. Further, the mass fractions of these pollutant species are usually very small and they have negligible influence on the flow fields. Hence, for steady-state simulations, the solution of the pollutant transport equations can be decoupled from the other equations and solved in a postprocessing step. Ansys Fluent offers several specific pollutant models (NOx, soot) with fixed chemical mechanisms. The detailed chemistry pollutant model allows pollutant postprocessing using any chemical kinetic mechanism.
The following limitations exist when using the detailed chemistry pollutant model:
The detailed chemistry pollutant model is only available with the steady-state solver.
Since pollutant chemistry is postprocessed on a steady-state solution, pollutant species cannot couple with the flow, energy, or any other field (for example, radiating soot).
It can be difficult to revert to the original settings of your case file after you have set up the decoupled detailed chemistry pollutant model. This limitation can be addressed by saving case and data files prior to setting up the decoupled detailed chemistry pollutant model.