Scattering of an ultrasonic beam from a curved interface
Choi, Hyung-Chul
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https://hdl.handle.net/2142/22851
Description
Title
Scattering of an ultrasonic beam from a curved interface
Author(s)
Choi, Hyung-Chul
Issue Date
1989
Doctoral Committee Chair(s)
Harris, John G.
Department of Study
Engineering, Mechanical
Discipline
Engineering, Mechanical
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
We calculate the wavefield scattered from a circular fluid-solid interface when it is struck by a well collimated ultrasonic beam, emitted from a transducer in the fluid. Both convex and concave interfaces (as seen from source) are considered. The radius of curvature of the interface is assumed to be sufficiently large that only reflection, transmission and the excitation of a leaky Rayleigh wave need be considered; the incident beam does not graze the interface. The incident beam is modeled as a two-dimensional wavefield whose initial profile is either Gaussian or rectangular. In both cases the aperture is assumed to be sufficiently large (in wavelengths) that a well collimated beam is radiated, and the interface is assumed to lie close enough to the aperture that it is struck by a wavefield that has not yet evolved into a cylindrical wave. The scattered wavefields are represented as multiple integrals and are evaluated asymptotically. Of particular interest is the formation of caustics and cusps by the reflected and transmitted rectangular beam when it is scattered by the concave interface. Also of particular interest is the propagation and radiation into the fluid of the Rayleigh wave excited on the convex interface.
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