Judy Cooper
Ansys Employee

Hi Shuai:

An inert can be included in a Chemkin mechanism by putting it in the thermo and transport files with a different name from its chemical twin (also in the species list for the mechanism).  If it is completely excluded from any reactions, you will get a warning when the mechanism is pre-processed that it does not participate in any reaction.  This is ok.  It can also be used as a third body and diluent (if fed at an inlet in the resulting simulation).

Best Regards,