Oxygen Volume Fraction in extinction models

[eliascm21]

In the extinction models the "Oxygen Volume Fraction" is compared against a limiting value.
I would like to ask how the "Oxygen Volume Fraction" is defined. Is it the fraction of Oxygen in the whole mixture or is it the fraction of Oxygen in the Fuel-Air (unburned) mixture?

Thank you in advance.

[drjfloyd]

The extinction check is done prior to combustion but after mixing (See Chapter 5 and Appendices E and F in the Tech Ref for a discussion on mixing). It is the O2 volume fraction of the mixed gas.

[eliascm21]

Does the mixed gas contain combustion products (that perhaps have been created in the previous time step)?

[rmcdermo]

Yes