Free-Wave Propagation in and Sound Radiation by Layered Media with Flow.

Abstract : The layered system is composed of elastic, viscous and acoustic layers bounded by upper and lower acoustic half-spaces. Uniform subsonic flows may be present in the acoustic layers and half-spaces. The method of dynamic stiffness coupling is used to obtain the system dynamic stiffness matrix which connects 'spectral' displacements and external stresses at the interfaces. Far-field sound radiation and the wavenumbers of free-waves are found from this matrix relation. Numerical results include wavenumber-frequency plots which exhibit the characteristics of instabilities. (Author)