We report on the results from a set of incompressible, shear-layer flow experiments, at high Reynolds number (Re δ ≡ ρ ∆U δ T (x)/µ 2 × 10 5 ), in which the inflow conditions of shear-layer formation were varied (δ T is the temperature-rise thickness for chemically-reacting shear layers). Both inert and chemically-reacting flows were investigated, the latter employing the (H 2 +NO)/F 2 chemical system in the kineticallyfast 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 chemicalproduct formation, far downstream of the inflow region.

Scale distributions of high- and low-dimensional transects of fluid interfaces in turbulence are analyzed and compared. For mixed-fluid interfaces derived from concentration measurements in turbulent jets at Re∼104 and Sc∼103, the relative coverage dimensions of spatial two-dimensional and one-dimensional transects agree at the smallest and largest scale, as expected, but are found to be different at intermediate scales: the higher-dimensionality transects have a larger relative coverage dimension and, in this sense, exhibit more structure. This behavior has implications for quantifying turbulent mixing in terms of the geometry of fluid interfaces.

The behaviour of an initially planar shock wave propagating into a linearly convergent wedge is investigated experimentally and numerically. In the experiment, a 25• internal wedge is mounted asymmetrically in a pressure-driven shock tube. Shock waves with incident Mach numbers in the ranges of 1.4-1.6 and 2.4-2.6 are generated in nitrogen and carbon dioxide. During each run, the full pressure history is recorded at fourteen locations along the wedge faces and schlieren images are produced. Numerical simulations performed based on the compressible Euler equations are validated against the experiment. The simulations are then used as an additional tool in the investigation.The linearly convergent geometry strengthens the incoming shock repeatedly, as waves reflected from the wedge faces cross the interior of the wedge. This investigation shows that aspects of this structure persist through multiple reflections and influence the nature of the shock-wave focusing. The shock focusing resulting from the distributed reflected waves of the Mach 1.5 case is distinctly different from the stepwise focusing at the higher incoming shock Mach number. Further experiments using CO 2 instead of N 2 elucidate some relevant real-gas effects and suggest that the presence or absence of a weak leading shock on the distributed reflections is not a controlling factor for focusing.