Geometrical Aspects of Scattering and Physical Effects of Sound
Annual summary rept. 1 Jun 97-31 May 98
WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
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Research is reported primarily in the following areas 1 High-frequency enhancements of the backscattering of sound by tilted empty and water-filled blunt elastic cylindrical shells in water are calculated and observed. The leaky-wave contributions to backscattering were studied and were also studied for a solid stainless-steel cylinder. A different type of backscattering enhancement was also studied for penetrable cylinders e.g. plastics supporting low-velocity waves. This enhancement is associated with a caustic-merging transition which was also confirmed with an analogous light scattering experiment. 2 The coupling of oscillating magnetic fields to the torsional modes of a stainless steel spherical shell in water was investigated. Sound radiated by the magnetically excited modes is detected and resonances are identified. 3 Some predicted properties of helicoidal ultrasonic waves were confirmed using a novel PVDF transducer. These waves have an axial null and have potential applications in scattering and alignment and they carry orbital angular momentum. Other research summarized concerns 4 acoustical-scattering analogs studied with light and 5 the acoustical probing of dilute aqueous suspensions of particles using radiation pressure.