Modeling the Effects of Thermal Expansion on Scalar Turbulent Fluxes in Turbulent Premixed Flames

Robin, Vincent; Mura, Arnaud; Champion, Michel; Hasegawa, Tatsuya

doi:10.1080/00102200903462896

Cited by 32 publications

(22 citation statements)

References 24 publications

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“…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. [40][41][42] Nevertheless, the DNS by Nishiki et al 28,36 suffered from a low ratio of the transverse width yz = 4 mm of the computational domain to the integral length scale L = 3.5 mm of turbulence. On the one hand, such a low ratio of yz /L is an obvious limitation.…”

Section: Simulationsmentioning

confidence: 99%

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

2014

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Database obtained earlier in 3D Direct Numerical Simulations (DNS) of statistically stationary, 1D, planar turbulent flames characterized by three different density ratios σ is processed in order to investigate vorticity transformation in premixed combustion under conditions of moderately weak turbulence (rms turbulent velocity and laminar flame speed are roughly equal to one another). In cases H and M characterized by σ = 7.53 and 5.0, respectively, anisotropic generation of vorticity within the flame brush is reported. In order to study physical mechanisms that control this phenomenon, various terms in vorticity and enstrophy balance equations are analyzed, with both mean terms and terms conditioned on a particular value c of the combustion progress variable being addressed. Results indicate an important role played by baroclinic torque and dilatation in transformation of average vorticity and enstrophy within both flamelets and flame brush. Besides these widely recognized physical mechanisms, two other effects are documented. First, viscous stresses redistribute enstrophy within flamelets, but play a minor role in the balance of the mean enstrophy within turbulent flame brush. Second, negative correlation u · ∇ between fluctuations in velocity u and enstrophy gradient contributes substantially to an increase in the mean within turbulent flame brush. This negative correlation is mainly controlled by the positive correlation between fluctuations in the enstrophy and dilatation and, therefore, dilatation fluctuations substantially reduce the damping effect of the mean dilatation on the vorticity and enstrophy fields. In case L characterized by σ = 2.5, these effects are weakly pronounced and is reduced mainly due to viscosity. Under conditions of the present DNS, vortex stretching plays a minor role in the balance of vorticity and enstrophy within turbulent flame brush in all three cases. C 2014 AIP Publishing LLC. [http://dx

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Section: Simulationsmentioning

confidence: 99%

“…28 and 36 and were already used in a number of recent papers, [37][38][39][40][41][42] we restrict ourselves to a brief summary of the simulations. The computational domain was a rectangular 8 × 4 × 4 mm and was resolved using a uniform rectangular mesh of 512 × 128 × 128 points.…”

Section: Simulationsmentioning

confidence: 99%

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

2014

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“…In particular, such an approach allows us to subsume not only the model by Veynante et al [46], who, following Bray [52], highlighted the difference between velocities conditioned on unburned and burned gas due to pressure drop across inherently laminar flamelets, but also a model by Zimont and Biagioli [53,54], who highlighted the difference between the conditioned velocities due to different accelerations of the unburned and burned gas by the combustion-induced mean pressure gradient within the mean flame brush. Recent models [49][50][51]55,56] address both mechanisms. For instance, Eq.…”

Section: Mathematical Formulation and Governing Equationsmentioning

confidence: 96%

“…Based on earlier studies [46][47][48][49][50][51], the turbulent scalar flux is closed as follows F t qu 00 c 00 ¼ À qD t @c @x þ qU Bc ð1 ÀcÞ:…”

Section: Mathematical Formulation and Governing Equationsmentioning

confidence: 99%

Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Sabelnikov

Lipatnikov

2015

Combustion and Flame

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“…Since the data were comprehensively discussed by various research groups, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] we will restrict ourselves to a brief summary of those compressible simulations. They dealt with statistically 1D, planar, adiabatic flames modeled by unsteady 3D continuity, Navier-Stokes, and energy equations, as well as the ideal gas state equation.…”

mentioning

confidence: 99%

Letter: Does flame-generated vorticity increase turbulent burning velocity?

et al. 2018

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Direct numerical simulation data obtained from a statistically stationary, 1D, planar, weakly turbulent, premixed flame, which is associated with the flamelet combustion regime, are analyzed in order to show that generation of vorticity due to baroclinic torque within flamelets can impede wrinkling the reaction surface, reduce its area, and decrease the burning rate. These data call for revisiting the widely accepted concept of combustion acceleration due to flame-generated turbulence.

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Modeling the Effects of Thermal Expansion on Scalar Turbulent Fluxes in Turbulent Premixed Flames

Cited by 32 publications

References 24 publications

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

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

Transition from pulled to pushed fronts in premixed turbulent combustion: Theoretical and numerical study

Letter: Does flame-generated vorticity increase turbulent burning velocity?

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