Ignition delay time using the peak method missing for some cases

[corykinney]

Currently ignition_delay_time with method="peak" calls np.argmax to find the time of maximum species mole fraction. This works in cases where the species mole fraction decreases after ignition; however, for some species, such as OH, concentration plateaus after ignition for some mechanisms with a very slight rise due to negligible but non-zero rate coefficients. In this case, the max of the concentration occurs at the final timestep. In this case, knightshock returns np.nan because it thinks that concentration is still rising, indicating ignition has not yet occurred.

Reported by @zuhayrpasha - could you respond with the temperature, pressure, and mixture that was causing this issue, and attach the Cantera mechanism file in the YAML format?

[zuhayrpasha]

Temperature: 1000K
Pressure: 60 bar
X = {'AR':0.5368,'C3H8':0.012,'CH3OCH3': 0.018,'O2':0.4332}
mech_dames.txt