The high-frequency description of scatter of a plane compressional wave by an elliptic crack.

High-frequency approximations that can be interpreted in terms of the Uniform Geometrical Theory of Diffraction (UGTD) and Uniform Kirchhoff Approximation (UKA) are used to develop a code for modeling ultrasonic scatter of a plane compressional wave by an elliptic crack in the radiating near field. The approximations are intercompared and partially validated against a direct numerical code based on an FD (Finite-Difference) scheme. At present, in many realistic situations the approximate codes of the type described here offer the only viable simulation tool; purely numeric codes are not only much slower, they still require too much computer memory to simulate the complex structure of the radiating near fields.
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