Recent Advances in Turbulent Mixing
نویسنده
چکیده
Experimental, modeling, and direct-numerical-simulation (DNS) studies have advanced our understanding of turbulence and mixing. The mixing transition, that occurs across a broad spectrum of flows, at outer-scale Reynolds numbers in the vicinity of Re δ ≈ 1 − 2 × 10 4 , or Taylor Reynolds numbers of Re T ≈ 100 − 140, will be discussed. Inflow-/initial-condition effects in high-Re shear layers will also be discussed. Comparisons between DNS studies of strained diffusion-flame regions and experiments in chemically reacting shear layers provide some new insight in the overall chemical-product formation. DNS studies of the Rayleigh-Taylor instability (RTI) between miscible fluids, with identical boundary conditions and different initial perturbations reveal an initial-growth regime dominated by diffusion, with a subsequent nonlinear growth that depends on the details of the initial perturbations for as long as the simulations were run. Mixing in RTI flow is found even more sensitively dependent on initial conditions. The discussion concludes with some general comments on high-Re turbulence.
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