Modeling acoustic wave propagation and reverberation in an ice covered environment using finite element analysis

Abstract

A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.