Efficient, wide-band rigid-body and elastic scattering computations using transient equivalent sources

A previous paper by the author has shown that transient structural-acoustic problems can be solved using time stepping procedures with the structure and fluid modeled using finite elements and equivalent sources, respectively. Here, the analysis is extended to included scattering problems. Although scattering problems have been discussed extensively in the literature, the current formulation is unique because the acoustic coupling matrix is treated as sparse. Also, most of the previous analyses have assumed the problem is time harmonic, and there is an advantage to performing the computations in the time domain because only a limited number of time steps are required to obtain wideband frequency resolution. This is especially true if the main emphasis is on the mid- to high-frequencies since the ringing response is typically dominated by the lowest frequency modes. Several examples are solved to validate the computations and to document the computation times and solution accuracy.