[Rickard.Solsjo]

I was reading the other threads but I still have some questions.
Are chem_inp and chem_inp15 subtitutes?
If I e.g. am using C12H26 the reaction is

C12H26+18.5O2 -> 12CO2 + 13H20...

Do I create the file
ELEMENTS
H O C N AR
END
SPECIE
C12H26O2 N2 CO2 H2O
END
REACTIONS
C12H26+18.5O2 -> 12CO2 + 13H20 5.00E+8 0.0 15780.0! 1
FORD / C12H26 0.25 /
FORD / O2 1.5 /
END

or something like this ? Under chem_inp 15 they have more reactions. Do I need these?

[marcbest]

i don't know the forwardreaction orders (FORD) for dodecane, you should look for a suitable reaction mechanism...

the chem.inp in tutorial aachen bomb is a global reacting mechanism. that means, that there are only reactants and productucts described.
the chem.inp_15 is a detailled reaction mechanism, where (all)many elementary reactions are described

the difference is that detailled mechanisms describe the case more precise, but as there are more species, more species-equations have to be solved, so the simulation takes longer

i think you should start with global mechanism, as you wrote in red, but maybe you have to check the arrhenius rates etc.