Implications of recent experimental results for modeling reactions in turbulent flows

Experimental results revealing new features of the mixing and combustion processes in fully developed shear layers and jets are reviewed and a discussion of the implications for modeling these flows is presented. Certain experimental results are cited which imply that molecular transport coefficients, particularly the diffusion coefficient, influence significantly the molecular mixing rate even at high Reynolds numbers. Also, the role of the large-scale inviscid motions in establishing the environment for the subsequent molecular mixing and in controlling the entrainment is emphasized. The entrainment and mixing processes in the flows is inherently unsteady on the largest spatial and temporal scales in each flow.