| Popis: |
The formalism of D. Chu [J. Acoust. Soc. Am. 86, 1883–1896 (1989)] is used to perform an investigation of the spatial and time domain variations of the scattered field of a penetrable isovelocity wedge. The direct, reflected, and diffracted field components are considered, and the relationships between them are investigated. The density contrast surface is an appropriate model for many water–seafloor interfaces and, since diffractions often dominate scattering from rough surfaces, an emphasis is placed on achieving an improved description and understanding of these waves. Particular emphasis is placed on a detailed study of the wave phenomena and transition behavior around the forward scattering shadow boundary, where the causal relationship between the direct incident field and the diffracted field is specifically examined. At the apex the two fields coincide, and their propagational effects here, and also above and below the geometrical shadow zone, lead to complicated temporal and azimuthal variations of the field. The origin and behavior of diffractions associated with specular reflections of the source in the faces of the wedge is also studied. [Work supported by ONR.] |
