[Svensson]

I would like to understand why we need and how arranged Ydefault file to 0 the case directory. I can not find documentation on this issue.

p.s.
In my problem I can see that it is somehow associated with the onset of combustion in reactingFoam project, but still do not understand how.

[kerstin]

It is like a placeholder for the species which are present in the reactions file, but not specified in the 0 folder.

e.g. you have a reaction

A + B = C + D + E

You specify in the reactions and chemkin files for the species, which components you have. You can just set Ydefault = 0 and the mass fraction of your initial species ( in my example its A and B) with some value and thats it...

Kerstin