Visualization of transient acoustic wave scattering from targets with thin shells

Abstract

The objective of this work is to gain qualitative and quantitative understanding of acoustic wave scattering from thin shells. Near-field solutions for a pulse excitation are obtained and plotted in a time series. The visualization demonstrates development of transient edge scattering, at close range, of a target that incorporates thin shells and sharp edges. The demonstration is of wide interest and in that, the advantages of the adopted time domain formulation become apparent. Within the calculation technique, pressure difference across the shell has been obtained by the point collocation procedure, based on a boundary integral equation solution for thin shells. The near-field solution is solved from the pressure difference through the classical Helmholtz equation of retarded potentials. The transient scattered field on a plane has then been visualized with a general meshing program. Objects employed include a flat circular disc, a flat rectangular disc, an open cone, and a thin-walled cylinder. Some of the calculations have been verified by comparing the harmonic response, which has been obtained via Fourier deconvolution of the transient far-field transfer function, with existing analytical solutions or experimental results.