Radical fingering in turbulent premixed flame classified into thin reaction zones

A direct numerical simulation study of vorticity transformation in weakly turbulent premixed flames

“…Since that, significant progress in the area of DNS of premixed turbulent combustion was made and the leading groups succeeded in directly computing highly turbulent flames by allowing for complex combustion chemistry. [43][44][45] When compared to the most advanced recent numerical simulations, the DNS analyzed by us is not state of the art. However, this fact does not mean that the data have no value today.…”

“…Accordingly, the range of Re t ≈ 100 reached in the DNS by Nishiki et al 28,36 is typical even for recent simulations. For instance, among eight papers that aimed at DNS of premixed turbulent flames and were published in the proceedings of the latest 34th Combustion Symposium, 45,[47][48][49][50][51][52][53] Re t was substantially larger than 100 only in two papers, 45,52 with the combustion chemistry being reduced to a single reaction in five papers. 47,[49][50][51]53 We may also note that the DNS data by Nishiki et al 28,36 were analyzed in several recent papers.…”

“…Nevertheless, as far as the goals of the present study are concerned, this limitation should not be overestimated, because (i) the governing phenomena, i.e., the baroclinic torque and dilatation, are localized to flame fronts, which are much thinner than the width yz , and (ii) small-scale effects are commonly less sensitive to the size of the computational domain. On the other hand, a low ratio of yz /L allowed Nishiki et al 28,36 to reach sufficiently large ratios of L/δ L , whereas the vast majority of recent DNSs 44,45,[47][48][49][50][51][52][53] …”

“…While the former case was selected in vast majority of recent DNS studies, 44,45,[47][48][49][50][51][52][53] the latter case addressed, in particular, by Nishiki et al 28,36 is also worth investigating. To conclude this section, let us compare the present simulations with previous DNS research [31][32][33][34] into vorticity transformation in premixed turbulent flames.…”

Turbulence–flame interaction and fractal characteristics of H2–air premixed flame under pressure rising condition

“…Three-dimensional DNSs have been conducted to investigate local flame characteristics in the thin reaction zones, the corrugated flamelets and the wrinkled flamelets for hydrogen-air premixed flames in our previous studies [2][3][4][5][6]. Shim et al [4] have shown that fluctuations of the heat release rate at the flame front in the thin reaction zones is relatively larger than that in the corrugated flamelets and the heat release rate of most of the flame elements are in the range of 0.9-1.1 times that of the laminar flame, while those in the corrugated flamelets and the wrinkled flamelets [2,3,5] have a value around that of the corresponding laminar flame.…”