Control of Two- and Three-Dimensional Wake Instabilities from Bluff-Bodies

This program addresses the manipulation of flow structure and spectral content of near and far wake instabilities from bluff bodies by: (1) generation of varying phase shift and wavelength of vortex shedding relative to body motion by sinusoidal, amplitude-modulated, and frequency modulated excitation; (2) alteration of mean boundary conditions at separation via boundary layer control; and (3) modification of three dimensional (spanwise) geometry of the body surface. In parallel with these technical objectives, new types of experimental techniques will be developed. Emphasis will be on laser diagnostics, and interactive image display and analysis exploiting new types of graphic supercomputers. Particular effort will be devoted to the development of a high resolution particle image velocimetry (PIV) system that allows acquisition of velocity information over entire planes of the flow. Two- and three-dimensional interpretations of the flow structure in color and real time are attainable using graphics supercomputers.