Journal of Fluid Mechanics

Turbulent shear-layer mixing at high Reynolds numbers: effects of inflow conditions

M. D. SLESSOR a1, C. L. BOND a1 and P. E. DIMOTAKIS a1
a1 Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA 91125, USA


We report on the results from a set of incompressible, shear-layer flow experiments, at high Reynolds number (Reδ[identical with]ρΔUδT(x)/ μ[simeq R: similar, equals]2×105), in which the inflow conditions of shear-layer formation were varied (δT is the temperature-rise thickness for chemically-reacting shear layers). Both inert and chemically-reacting flows were investigated, the latter employing the (H2+NO)/F2 chemical system in the kinetically-fast regime to measure molecular mixing. Inflow conditions were varied by perturbing each, or both, boundary layers on the splitter plate separating the two freestream flows, upstream of shear-layer formation. The results of the chemically-reacting ‘flip experiments’ reveal that seemingly small changes in inflow conditions can have a significant influence not only on the large-scale structure and shear-layer growth rate, as had been documented previously, but also on molecular mixing and chemical-product formation, far downstream of the inflow region.

(Received February 9 1998)
(Revised June 29 1998)