  This paper analyzes turbulence-chemistry interactions for an n-dodecane-air
flame, focusing on the degree to which fuel oxidation pathways change in
turbulent flames relative to their corresponding laminar flames. This work is
based on a lean n-dodecane-air flame DNS database from Aspden et al. (Proc.
Combust. Institute, 36 (2017) 2005-2016). The relative roles of dominant
reactions that release heat and produce/consume radicals are examined at
various turbulence intensities and compared with stretched flame calculations
from counterflow flames and perfectly stirred reactors. These results show that
spatially integrated (i.e. integrated heat release or radical production rate
metrics averaged over the entire flame) chemical pathways are relatively
insensitive to turbulence intensity and mimic the behavior of stretched flames.
In other words, the contribution of a given reaction to heat release or radical
production, integrated over the entire flame, is nearly independent to
turbulence. Localized analysis conditioned on topological feature of the flame
and on temperature is also performed. The former analysis reveals that much
larger alteration of pathways occurs in the positively-curved regions of the
flame. The latter localized analysis shows that peak activity in the low
temperature (i.e. below 1200K) region shift towards higher temperatures with
increases in Karlovitz number. This result is particularly interesting given
that prior work with lighter fuels showed the opposite behavior suggesting a
disparate response of the reactions involved in the fuel oxidation process to
increased turbulence.
