ASA 125th Meeting Ottawa 1993 May

2pPA8. Influence of sound-speed fluctuations and medium geometry on wave localization.

Kavitha Chandra

Charles Thompson

Lab. for Advanced Comput., Univ. of Massachusetts, Lowell, MA 01854

The influence of spatial geometry and material composition on acoustic radiation is considered. Numerical methods are presented that compute the scattered wave field for wavelengths between the Rayleigh scattering and geometrical optics regimes. The transition from extended to localized modes and their dependence on the wave number, average sound-speed fluctuations, and volume fraction of the scatterers is demonstrated. It is shown that the sound-speed contrast must exceed a minimum value for the localized modes to exist. A spatially varying eigenfunction decomposition of the intensity field is carried out to demonstrate this localization effect.