Zone conditional assessment of flame-generated turbulence with DNS database of a turbulent premixed flame

Statistics of Conditional Fluid Velocity in the Corrugated Flamelets Regime of Turbulent Premixed Combustion: A Direct Numerical Simulation Study

“…It is worth stressing that these velocities were evaluated in the coordinate framework selected so that the mean velocity of unburned gas upstream the flame brush is equal to S L . It is evident from Figure 5(a) that the simplest model given by (11b) [10] captures the behaviour of (u 1 ) Rs /S L for the major portion of the flame brush, which is in agreement with earlier DNS results [6,7]. Figure 5(a) show that the performance of (11c) is comparable for c = c and c = c and the model given by (11c) underpredicts (u 1 ) Rs /S L for the case considered here.…”

“…As proposed in [10] based on the DNS data by Im et al [6], the simplest possible model for the surface averaged velocity components conditional on unburned gas side of flamelets (i.e. (u i ) Rs ) can be given as follows:…”

“…Mean fluid velocities conditional in reactants, products, and instantaneous flame surface often play a key role in the theoretical analysis and modelling of turbulent premixed combustion [1][2][3][4][5][6][7]. Theoretical analysis of Bray et al [1] demonstrated the relation between the turbulent scalar fluxes ρu i c of reaction progress variable c and the difference in the mean conditional velocities in products and reactants ((u i ) P − (u i ) R ), where the overbar signifies a Reynolds averaging operation, q = q − q, q = q − q, and q = ρq/ρ are the Reynolds fluctuation, Favre fluctuation, and Favre mean of a general quantity q, u i is the ith component of velocity, ρ is the gas density, and the subscripts R and P are used to refer to conditional mean quantities in reactants and products, respectively.…”

“…In addition to the conditional mean velocities (i.e. (u i ) R and (u i ) P ), the surface averaged quantities play a pivotal role in the closure of turbulent premixed flames using the Flame Surface Density (FSD) [3,5,8,9] or conditional mean equations [6,7,[10][11][12][13].…”

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

“…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.…”