P. R. Stepanishen
Dept. of Ocean Eng., Univ. of Rhode Island, Kingston, RI 02881
Acoustic harmonic nonaxisymmetric scattering from rigid shells of revolution is addressed using the generalized internal source density and SVD method. The development of the generalized ISD/SVD method, which entails the use of various internal multipole source distributions along the axis of the shell, will be presented. The approach is based on first expanding the incident pressure and associated velocity field into circumferential harmonics about the axis of the shell. Integral equations of the first kind are developed for the unknown source distributions. A least-mean-squared error formulation of the solution naturally leads to using the SVD method to determine the source distributions. The blocked surface pressure for each circumferential harmonic is then readily evaluated by simple quadrature methods and the associated far-field scattered pressures are shown to be simply related to the Fourier transforms of the source distributions. Numerical results for some selected problems are presented and some limitations of the method as a function of azimuthal wave number and shape of the shells are noted. These limitations are discussed and are readily interpreted in light of the above-noted Fourier transform relationship.