how does the ignition model initiate main combustion
 

Dear all,

Im using StarCD for GDI engine combustion simulation. I use EBU model for main combustion and select the numerical ignition as a spark.
My question it, how does the ignition model trigger the main combustion. As is stated in methodology, ignition is accomplished when a portion of the fuel at the spark is consumed. Apart from this, does the ignition has anything to do with the local air-fuel ratio? Are mass,momentum,energy equivalence considered between the spark cells and the chamber cells that enough energy should be created at the spark to trigger main combustion, or is the ignition determined only numerically from the mass of fuel burnt at the spark?

Thanks