Scattering of acoustic waves by a prolate body in plane-stratified waveguide

Technique for calculation of diffraction field by spatially localized inhomogeneity is proposed. This technique is based on the fact that the scattering matrix of the waveguide mode is expressed through the scattering amplitude in free space. This permits separation of the diffraction problem in free space and the propagation problem in the waveguide (the problem of calculation of waveguide modes). Requirements for sound-speed variation and for distance between scatterer and waveguide boundaries are formulated. On the basis of the energetic approach, the concept of the cross section in the waveguide is proposed. The coupling modes and sound absorption are discussed as well. The space-time structure of a sound field scattered by the moving localized inhomogeneity in the direction of incident wave (the forward scattering) is given and discussed. As an example, structure of the sound field for a scatterer modeled by spheroid prolate for different parameters of waveguides is calculated. [Work supported by RFBR, Grant 99-02-17671.]