Modeling ICE ignition
 

بسم الله الرحمن الرحيم

During simulation of In-Cylinder ICE (2000 RPM) problem.
when selecting(Finite-Rate/Eddy-Dissipation) in Species Reaction model
Mixture material -> n-heptane-air (5 volumetric species)

Entering the inlet boundary condition
Intake -> Pressure inlet = 0 guage
Species -> C7H16 = 0.0621 , O2=0.2186 (which is the stoich. mass fraction)

also, activating the Spark Ignition Model
Model -> fixed Spark Size
Shape Parametrs -> (X,Y) =(0,0), r = 0.001 m
Model Parameters -> Energy=0.1 J
Start degree = 700 deg
Duration =0.001 s
Diffusion Time=1e-5 s

I find that the reaction does not occurs
unless assigning the Spark Energy exceeds 1000 J

Is this value of spark energy is true?
In fluent user guide the Energy=0.1 J
In (Stephen RTurns - An Intrduction to Combustion) Table 8.5 P294
for n-Heptane at 298K the Eign = 14.5 milli J

The question is Why this great ratio between actual and theoretical Eign which exceeds 10^4.

thanks for any one answers me