Discrete‐element acoustic analysis of submerged structures using doubly asymptotic approximations

Doubly asymptotic approximations have been found to offer significant advantages for the treatment of steady‐state fluid‐structure interaction in vibration, acoustic‐radiation, and acoustic‐scattering problems for complex submerged structures. This paper describes the theoretical foundations, development, and verification of two boundary‐element/finite‐element processors that implement this approach. The first processor is SWEEPS, which determines the structural response of and surface pressure on a vibrating submerged body using an iterative, incremental frequency technique for computational efficiency. The second is TARGET, which embodies a discretized form of the Helmholtz integral equation to obtain fluid pressures away from the body. To test these processors, two problems involving a spherical shell in an infinite fluid have been solved. The first problem is one of modal internal forcing; while the second is concerned with forcing by incident plane waves. The computational results exhibit excellent agreement with closed form solutions.