Numerical investigation of transmission of low frequency sound through a smooth air-water interface

Abstract

It is the traditional belief that sound transmission from water to the air is very weak due to a large contrast between air and water impedances. Recently, the enhanced sound transmission and anomalous transparency of air-water interface have been introduced. Anomalous transparency of air-water interface states that the sound generated by a submerged shallow depth monopole point source localized at depths less than 1/10 sound wavelength, can be transmitted into the air with omni-directional pattern. The generated sound has 35 times higher power compared to the classical ray theory prediction. In this paper, sound transmission through air-water interface for a localized underwater shallow depth source is examined. To accomplish this, two-phase coupled Helmholtz wave equations in two-phase media of air-water are solved by the commercial finite element based COMSOL Multiphysics software. Ratios of pressure amplitudes of different sound sources in two different underwater and air coordinates are computed and analyzed against non-dimensional ratio of the source depth (D) to the sound wavelength (λ). The obtained results are compared with the experimental data and good agreement is displayed.

Low-frequency sound transmission through rough bubbly air–water interface at the sea surface

“…Viewed from the air, the same surface would be called acoustically "hard". 2 In recent years, the anomalous transparency 1,[3][4][5] and enhanced sound transmission [6][7][8] theories for sound transmission through air-water interface have been introduced. In these theories, despite the mentioning of the classical view of air-water interface, it is anticipated that most of the acoustic power in a liquid half-space for a low frequency sound generated near the interface within a fraction of wavelength can be radiated into a gas half-space.…”

Simulation of wind-generated surface waves and effects of bubbles on scattering, transmission, and attenuation of low frequency sound at the sea surface

“…The wide range of subjects in this area, e.g., underwater communication channels [2][3][4][5][6][7][8], evaluation of sonar performance [9][10][11], marine life [12][13][14], oceanography [15][16][17] among others, has led to numerous researches which have concentrated on these influential phenomena on the sound. Doppler effects [18][19][20][21], attenuation and absorption [22][23][24][25], bubble population [26][27][28][29], and sound transmission [12,[30][31][32][33] as well as the environmental conditions such as wave propagation in shallow water [2,[34][35][36], surface waves [37][38][39][40], and bottom effects [41][42][43] can be considered as interesting Abstract Sea surface virtual acoustic simulator lab (SSVASL) is a software based on a newly presented reformed Helmholtz-Kirchhoff-Fresnel method developed in FORTRAN programming language. Based on the resonance dispersion model (RDM), bubbles d...…”