An acoustic finite‐element model to study sonar interactions with marine mammals.

A computer model based on the finite‐element method (FEM) is being developed to study the interaction of sonar signals with marine mammals. This model solves the Helmholtz equation in a computational box that includes the animal and the surrounding medium, water. The FEM code has been validated with analytical solutions for the scattering of a plane wave by a fluid sphere over a range of parameters and frequencies of interest. Then it has been applied to a specimen, a 142‐cm‐long common dolphin (Delphinus delphis), and internal pressure and displacement fields were computed. The animal is represented in the computer model by a set of tissue groups whose acoustic properties, density, and sound speed are taken from the literature. The geometry of each tissue group was constructed from segmented computerized tomography images. Results are presented for harmonic signals in the 1–10 kHz frequency range. [Work supported by NOPP through ONR award No. N000140710992.]