Index of content:
Volume 115, Issue 5, May 2004
- SELECTED RESEARCH ARTICLES 
115(2004); http://dx.doi.org/10.1121/1.1651116View Description Hide Description
The educational value of time–domain animations for visualizing acoustic impulse scattering from spheres, and the formation of scattered wave fronts, is demonstrated. Anderson’s fluid sphere theory [J. Acoust. Soc. Am. 22, 426–431 (1950)] is used to demonstrate scattering for two cases: (a) a fixed rigid sphere; (b) a pressure release sphere. The backscattering regime is seen to be dominated by geometric reflections. In the forward scatter region, visualizations for both cases show that the incident and forward scattered fields combine to rapidly minimize amplitude and phase perturbations of the wave front, leading to “wave front healing.” Diffraction into the acoustic shadow behind the sphere is seen and, in the rigid case, leads to a clearly discernible circumferential wave that breaks off in the backward direction. Animations based upon the raypath scatter method depict how this technique represents geometrical reflections, while omitting diffraction effects, but appears to be a reasonable approximation for backscattering applications. The Hickling and Wang “movable” rigid sphere theory [J. Acoust. Soc. Am. 39, 276–279 (1966)] is used to create an animation that illustrates the “rebound” response motion of a sphere of finite mass to the action of the incident field. The animations discussed are downloadable via the World Wide Web.