ASA 127th Meeting M.I.T. 1994 June 6-10

4aSA9. Numerical estimates---based on ray methods---for the scattered acoustic fields of pairs of targets.

G. C. Gaunaurd

H. Huang

Naval Surface Warfare Ctr., Dahlgren Div., Res. Dept., Silver Spring, MD 20903-5640

H. C. Strifors

Natl. Defense Res. Establishment, S-17290, Sundbyberg, Sweden

The sounds fields scattered by a multiplicity of spherical bodies can be predicted in an exact analytic fashion. This was illustrated in a previous presentation (cf., the paper entitled ``Exact Analysis of the Acoustic Scattering Produced by Arbitrarily Insonified Bodies Near Boundaries,'' by Huang and Gaunaurd (in this session), which also included the exact analysis for two spheres in free space, at arbitrary frequencies, and accounting for multiple scattering interactions. That work was mainly concerned with the low- and mid-frequency regimes. However, at the high frequencies for which certain asymptotic approximations begin to hold true, one can construct relatively simple-looking expressions for the sound fields scattered by pairs of spherical bodies. These expressions become even simpler looking for bodies separated by distances larger than their sizes. Even when this is not the case, the asymptotic results seem to hold just as well. The final estimates are: (a) evaluated numerically, (b) compared to (now available) exact analytic solutions, (c) graphically displayed, and (d) physically interpreted. These estimates are the acoustical counterparts of analogous ones in the radar literature and they are useful to determine the minimal separation at which remote sensors can actually discriminate two (or more) interacting neighboring targets. [Work partially supported by the NSWC IR Program.]