Transient radiation and scattering from fluid-loaded spherical and cylindrical shells

Abstract

Transient radiation and scattering from fluid-loaded spherical and cylindrical shells has been the subject of numerous investigations during the past 30 years. A new time domain method of addressing these problems is presented here where the velocity field of the shell in fluid is represented as an in vacuo modal vector expansion with time-dependent coefficients. For the two-dimensional problems of present interest, sets of two coupled convolution integral equations are developed for the time-dependent modal velocity coefficients. These equations are readily solved by a “marching forward in time” method. The often used plane wave and DAA methods are shown to be special cases of the present formulation. Numerical results are presented for the velocity and pressure field response of a point-excited spherical shell and a plane-wave-excited cylindrical shell. These results will illustrate the transition from light to heavy fluid loading on the transient response of the shells. [Work supported by ONR.]