LAUSR

A full understanding of differential molecular diffusion (DMD) in turbulent combustion has its theoretical significance for improving models of turbulent combustion. The scaling of the effect of DMD with respect to the Reynolds number in turbulent combustion is of particular interest for developing physically consistent modeling approaches for DMD. Such a scaling has so far been mostly studied in simple nonreacting flow problems, and a simple power-law scaling has been reported before. The applicability of the power-law scaling to turbulent combustion problems where the chemical reaction is expected to strongly couple with DMD has not been thoroughly studied. In this work, we aim to examine such a scaling by developing a statistical analysis of the dependence of DMD on the Reynolds number in turbulent nonpremixed combustion. Three Sandia temporally evolving planar jet nonpremixed CO/H2 direct numerical simulation flames [E. R. Hawkes et al., Proc. Combust. Inst. 31, 1633 (2007)] are chosen as the target flames for the study. The Reynolds-number scaling based on a statistical analysis is reported, which is found to be statistically consistent with previous theoretical results in nonreacting problems. The results provide supportive evidence to the existence of a universal power-law scaling of the effect of DMD with respect to the Reynolds number in turbulent nonreacting and reacting flow problems. The results are also important for constraining the development of Reynolds-number-scaling consistent physical models for treating DMD in the modeling and simulations of multicomponent turbulent diffusion systems.