Autoignition phenomena in engines are due to the effects of chemical kinetics of the reacting flow inside the cylinder. There are two types of autoignition models considered in Ansys Fluent:
knock model in spark-ignited (SI) engines
ignition delay model in diesel engines
For information regarding using autoignition models, see Using the Autoignition Models in the User's Guide. The theory behind the autoignition models is described in the following sections: