| Receptivity is the process by which external excitation disturbances couple with flow instabilities. Mixing layer receptivity plays a fundamental role in resonant shear flows such as cavity flow and supersonic jet screech. A complete model of any such phenomenon and the ability to control such flows both require knowledge of the efficiency of excitation of the free shear instability driving the resonance.; The present research takes a primarily computational approach to examining receptivity in a compressible mixing layer, and includes exploration of both direct excitation by sources near the mixing layer as well as acoustic receptivity via the edge-scattering process. An efficient method for calculating parallel flow receptivity based on adjoint solutions is adapted for analysis of the compressible mixing layer, allowing prediction of receptivity trends with Mach number, temperature ratio, co-flow, source type and location, and frequency.; The adjoint approach has been extended to the case of a splitter plate flow, where the linear receptivity characteristics are obtained by solving an adjoint wave scattering problem. Adjoint solutions for a supersonic mixing layer are examined in detail, demonstrating the utility of the method for both quantitative prediction of receptivity and physical interpretation of the salient receptivity mechanisms. Receptivity to large amplitude acoustic waves is then explored by direct simulation, revealing an amplitude threshold for nonlinearity in the mixing layer response. |
