Coupling of sound and internal waves in shear flows

Gravity waves in the parallel shear flow of a continuously stratified compressible fluid are considered. It is demonstrated that the shear induces a coupling between the sound waves and the internal gravity waves. The conditions for the effectiveness of the coupling are defined and a corresponding linear mechanism of wave transformation and energy transfer between the modes is described. It is also shown that, under suitable conditions, beat waves can be generated. (author). 28 refs, 5 figs