Physical Optics and Rigid/Soft Approximations to Forward Scattering by Elastic Shells.

摘要

Our numerical results demonstrate that both Fraunhofer and Fresnel diffractions provide good approximations to forward scattering by elastic spherical shells and rigid/soft spheres, for nondimensional frequency values 20<ka<-80, and scattering angles 0 deg < 0 <10 deg. There are only small differences among the Fraunhofer, Fresnel, and rigid/soft predictions for differential scattering cross sections. They arise mainly from the slightly varying degrees of compression (in angular space) of one pattern relative to another. The magnitudes of the maximums predicted by the four methods are in good agreement, but the minimums do not agree. Calculations for 1%, 5%, and 10% spherical steel shells indicate the variation of shell thickness has only a small effect on forward scattering. Signal processing, Classification, Antisubmarine warfare, Underwater acoustics.