ACOUSTIC SCATTERING BY SUBMERGED ELASTIC CYLINDRICAL-SHELLS - UNIFORMRAY ASYMPTOTICS

In a uniform ray acoustic formulation, the pressure field scattered by a submerged thin elastic cylindrical shell is comprised of a specular reflected wave field, a phase-matched leaky wave field, and a reflect ed-leaky wave interacting field. They correspond to the contribution f rom a saddle point, the residue from spectral poles, and the effect du e to their proximity in the spectral ray integral generating the refle cted field. Using plane wave far-field scattering as an example, this paper presents an improved uniform algorithm that expresses the third component in terms of the first and second, which have been developed earlier, plus a complementary error function. In addition, the creepin g wave contribution is also considered. Numerical implementation is ca rried out, showing extensively the scattered field data, in particular , their dependence on frequency as well as on aspect and azimuthal ang les; the ray constituents and interacting fields are identified indivi dually, thereby clarifying the relevant wave processes at various para meter regimes. It is observed that the uniform ray scheme improves con siderably over simple ray asymptotics, especially at lower frequencies , and that its prediction agrees very well with the exact solution for ka greater-than-or-equal-to 3.