  LES/PDF approaches can be used for simulating challenging turbulent
combustion configurations with strong turbulence chemistry interactions.
Transported PDF methods are computationally expensive compared to flamelet-like
turbulent combustion models. The pre-partitioned adaptive chemistry (PPAC)
methodology was developed to address this cost differential. PPAC entails an
offline preprocessing stage, where a set of reduced models are generated
starting from an initial database of representative compositions. At runtime,
this set of reduced models are dynamically utilized during the reaction
fractional step leading to computational savings. We have recently combined
PPAC with in-situ adaptive tabulation (ISAT) to further reduce the
computational cost. We have shown that the combined method reduced the average
wall-clock time per time step of large-scale LES/particle PDF simulations of
turbulent combustion by 39\%. A key assumption in PPAC is that the initial
database used in the offline stage is representative of the compositions
encountered at runtime. In our previous study this assumption was trivially
satisfied as the initial database consisted of compositions extracted from the
turbulent combustion simulation itself. Consequently, a key open question
remains as to whether such databases can be generated without having access to
the turbulent combustion simulation. Towards answering this question, in the
current work, we explore whether the compositions for forming such a database
can be extracted from computationally-efficient low-dimensional simulations
such as 1D counterflow flames and partially stirred reactors. We show that a
database generated using compositions extracted from a partially stirred
reactor configuration leads to performance comparable to the optimal case,
wherein the database is comprised of compositions extracted directly from the
LES/PDF simulation itself.
