I am modeling partially premixed combustion of propane-air using the 2-step propane-air mechanism in Fluent's library and the EDC model, and I have come across some strange results. When looking at the net rate of reaction of propane, I found that both positive and negative values were present. I'm not sure what this means physically. Is it saying that propane is both created and destroyed??? This would be impossible though. I checked the mass and energy flux balances, and both are very low. Everything seems converged at second order. Any information would be appreciated.