Proceedings ArticleDOI
Acoustic modeling of sandy ocean sediments
N.P. Chotiros
- pp 231-236
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TLDR
In this paper, a redefinition of the boundary between frame and fluid was found to provide a plausible explanation for the discrepancies of the fluid and elastic solid approximations, which will be useful in future applications involving acoustic interactions at the seafloor.Abstract:
Acoustic interaction with the seafloor is an integral part of underwater sound propagation. The reflection coefficient at the seafloor interface is a significant component of sound propagation loss, especially in coastal areas where the water depth is limited. The reflection coefficient may be used to characterize the properties of the seafloor for many undersea applications. In all cases, the quality of the result depends on the ability to accurately model the acoustics of the seafloor. Sandy sediments are of particular interest because current models are not consistent with measurements, signifying that our understanding of the physical processes is still inadequate. The discrepancies of the fluid and elastic solid approximations are clearly demonstrable. A poro-elastic model, such as Biot's theory, is more likely to succeed because sandy sediments are porous structures saturated with water. Using laboratory and at-sea measurements, an incompatibility between model and measurements was found. A redefinition of the boundary between frame and fluid was found to provide a plausible explanation. This work is expected to lead to a physically sound model of sediment acoustics, which will be useful in future applications involving acoustic interactions at the seafloor.read more
Citations
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Journal ArticleDOI
The calibration of a laser light line scan method for determining local interface roughness of the ocean floor
S.M. Varghese,Marcia J. Isakson +1 more
TL;DR: In this article, an interface roughness measurement system was developed in which a laser light sheet is projected onto the ocean floor, and a resulting image can then be analyzed to determine the interfaces roughness, which could greatly aid in determining the local interface profile for in situ acoustic scattering experiments.
ReportDOI
High-Frequency Acoustics of Ocean Sediments and Biot's Theory
TL;DR: In this paper, a physical model of high-frequency sound interaction with the seafloor including, penetration through the water-seafloor interface, as well as propagation within and scattering from the sea floor is presented.
References
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Journal ArticleDOI
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TL;DR: In this article, a theory for the propagation of stress waves in a porous elastic solid containing compressible viscous fluid is developed for the lower frequency range where the assumption of Poiseuille flow is valid.
Journal ArticleDOI
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Journal ArticleDOI
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D. C. Beard,P. K. Weyl +1 more
TL;DR: In this article, an investigation was made of the relations among porosity, permeability, and texture of artificially mixed and packed sand, to determine the approximate porosity and permeability values to be expected for unconsolidated sand of eight grain-size subclasses and six sorting groups.
Journal ArticleDOI
Force Fluctuations in Bead Packs
Chu-heng Liu,Sidney R. Nagel,D. A. Schecter,Susan Coppersmith,Satya N. Majumdar,Onuttom Narayan,Thomas A. Witten +6 more
TL;DR: In this model, the fluctuations in the force distribution arise because of variations in the contact angles and the constraints imposed by the force balance on each bead in the pile.
Journal ArticleDOI
The Scattering of Sound from the Sea Surface
TL;DR: In this article, the scattering coefficient of long-wave sound is calculated and shown to be σ σ 2k 2/4π 2∫∫Φ(ξη)exp[−ik(aξ+bη)]dξdη, where 2π/k is the wavelength of the sound, and a, b, c are the sum of the x, y, z direction cosines of the incident and scattered rays.