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TURBULENT FLUID INTERFACES AND REGIONS IN AERO-OPTICS AND MIXING

Haris J. Catrakis
Aeronautics and Fluid Dynamics Laboratories, Mechanical and Aerospace Engineering Henry Samueli School of Engineering, University of California, Irvine, CA 92697, USA

Roberto C. Aguirre
Aeronautics and Fluid Dynamics Laboratories, Mechanical and Aerospace Engineering Henry Samueli School of Engineering, University of California, Irvine, CA 92697, USA

Jennifer C. Nathman
Aeronautics and Fluid Dynamics Laboratories, Mechanical and Aerospace Engineering Henry Samueli School of Engineering, University of California, Irvine, CA 92697, USA

Philip J. Garcia
Aeronautics and Fluid Dynamics Laboratories, Mechanical and Aerospace Engineering Henry Samueli School of Engineering, University of California, Irvine, CA 92697, USA

Abstract

Properties of turbulent fluid interfaces and regions are investigated experimentally and theoretically with applications to aero-optics and mixing. Two large-scale flow facilities enable the examination of refractive interfaces and diffusive interfaces in fully-developed gas-phase and liquid-phase turbulent separated shear layers and jets, i.e. at flow conditions above the mixing transition. The separated shear layer and the jet are key flow geometries, respectively, for practical problems in aero-optics and mixing. Basic relations are considered regarding the surface area of the interfaces, the volume of fluid regions bounded by the interfaces, and the physical interfacial thickness. These quantities have different sensitivities to large scales and small scales. Resolution-scale effects are also considered based on scale-local density functions corresponding to each quantity. For the aero-optically generated fields, the experimentally-derived large-scale contributions to the wave-front distortions are interpreted in terms of a physical model based on the regions bounded by high-gradient refractive interfaces. For the turbulent-mixing fields, the dynamical behavior of the volume of the region of mixed fluid exhibits strong robustness to resolution-scale effects. The present experimental database, physical-modeling approaches, and findings indicate that the large-scale properties of turbulent interfaces and regions can be directly examined and quantified at large Reynolds numbers.