Principal strain rate evolution within turbulent premixed flames for different combustion regimes

The statistical behaviors of the principal strain rates and its evolution in turbulent premixed flames have been analyzed using a three-dimensional direct numerical simulations dataset statistically planar with different turbulence intensities spanning from corrugated flamelet regime to thin reaction zone regime. It has found that scalar gradient predominantly aligns collinearly most extensive rate eigendirection within flame for large values Damköhler numbers small Karlovitz numbers. However, this tendency weakens increasing intensity, which, given integral length scale, amounts decrease (an increase) (Karlovitz) number. Moreover, it observed terms due molecular diffusion, pressure Hessian, correlation between density gradients play key roles relative importance arising Hessian vorticity contributions transport diminishes number decreasing mean equation explained based on alignments eigenvectors vorticity, gradient, tensor. findings current analysis suggest tensor flames, their influence needs be accounted high fidelity modeling tangential scalar–turbulence interaction surface dissipation equations, respectively. This provides possible explanations modification alignment reactive local comparison non-reacting flows.