2018/06/15 by Sabelnikov, Vladimir, Yu, Rixin, Lipatnikov, Andrei
#FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn)
paper · doi:10.48550/arxiv.1806.05963
In a highly turbulent medium characterized by a low Damköhler number Da, reactions are commonly considered to occur in distributed zones broadened by small-scale turbulent eddies. In the present communication, an alternative regime of propagation of reaction waves in a highly turbulent medium is introduced and studied theoretically and numerically. More specifically, propagation of an infinitely thin reaction sheet in a turbulent medium is analyzed, with molecular mixing of the reactant and product being allowed in wide layers. In this limiting case, an increase in the consumption velocity by turbulence is solely controlled by an increase in the reaction-sheet area. Based on physical reasoning and estimates, the area is hypothesized to be close to the mean area of an inert iso-scalar surface at the same turbulent Reynolds number. This hypothesis leads to a relation for the turbulent consumption velocity, which is similar to the well-known Damköhler scaling associated commonly with distributed reaction zones at a low Da. The obtained theoretical results are validated by analyzing a big database (23 cases characterized by 0.01