Theory of Creeping Waves in Acoustics and Their Experimental Demonstration

Abstract

The theory of creeping waves is developed by applying the Sommerfeld-Watson transformation on the normal-mode solution for acoustic scattering from an infinite elastic cylinder. Two types of radiating, circumferential waves emerge: (1) highly attenuated “Franz-type” waves with subsonic speeds, and (2) supersonic “Rayleigh-type” waves which are only slightly attenuated. The experimental study of these waves for an aluminium cylinder is accomplished by two independent methods: (1) time measurements of sequential pulses, and (2) direct visualization by Schlieren techniques. Measured velocities, attenuations, critical angles, and scattering cross sections are compared with theoretical calculations. © 1969, Walter de Gruyter. All rights reserved.