A numerical investigation of stretch effects in counterflow, premixed laminar flames

Abstract

We use direct numerical simulation of propane/air flames with full chemistry in the geometry of stagnation flow to investigate the effect of different definitions of local flame stretch in the presence of spatially varying velocity gradients. Specifically, we compare simulations with potential- and plug-flow inlet conditions, and show that the widely used definition of upstream stretch leads to unphysical results for flames having the ‘same’ stretch. We then show that a reasonable re-definition of local stretch allows us to produce the ‘same’ flame in the presence of the ‘same’ stretch.