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Comparison of theories for acoustic wave propagation in gassy marine sediments

Comparison of theories for acoustic wave propagation in gassy marine sediments
Comparison of theories for acoustic wave propagation in gassy marine sediments
More than three decades ago, Anderson and Hampton [1, 2] (A&H) presented theories for wave propagation in gassy water, saturated sediments and gassy sediments in their two part review, which has been cited by many researchers in the geoacoustics and underwater acoustics areas. They gave an empirical formulation based on the theory of Spitzer [3] for the wave propagation in gassy water by adapting that for a viscoelastic, lossy medium. Following Leighton [4], this paper presents a theory based on non-stationary nonlinear dynamics of spherical gas bubbles and extends that 2007 paper to include liquid compressibility and thermal damping effects. The paper then shows how that nonlinear formulation can be reduced to the linear limit, and derives the expressions for the damping coefficients, the scattering cross section, the speed of sound and the attenuation, and compares these with the A&H theory. The current formulation has certain advantages over A&H theory such as implementing an energy conservation based nonlinear model for the gas pressure inside the bubble, having no sign ambiguity for the speed of sound formula (which is important when estimating the bubble void fraction) and correcting the ambiguity on the expression for scattering cross section, as identified in the recent work of Ainslie and Leighton [5]. Moreover, the theory presented here forms a basis for a nonlinear, time-dependent acoustic estimation model for gas bubble distributions in viscoelastic mediums since it avoids the commonly encountered assumptions on the bubble dynamics such as linearity, steady-state behaviour and monochromaticity.
gassy sediments, nonlinear propagation, acoustic scattering
Dogan, Hakan
a1e136a9-aab8-4942-a977-0ae3440758cc
Leighton, T.G.
3e5262ce-1d7d-42eb-b013-fcc5c286bbae
White, P.R.
2dd2477b-5aa9-42e2-9d19-0806d994eaba
Dogan, Hakan
a1e136a9-aab8-4942-a977-0ae3440758cc
Leighton, T.G.
3e5262ce-1d7d-42eb-b013-fcc5c286bbae
White, P.R.
2dd2477b-5aa9-42e2-9d19-0806d994eaba

Dogan, Hakan, Leighton, T.G. and White, P.R. (2014) Comparison of theories for acoustic wave propagation in gassy marine sediments. 2nd International Conference and Exhibition on Underwater Acoustics (UA2014), Greece. 22 - 27 Jun 2014. 10 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

More than three decades ago, Anderson and Hampton [1, 2] (A&H) presented theories for wave propagation in gassy water, saturated sediments and gassy sediments in their two part review, which has been cited by many researchers in the geoacoustics and underwater acoustics areas. They gave an empirical formulation based on the theory of Spitzer [3] for the wave propagation in gassy water by adapting that for a viscoelastic, lossy medium. Following Leighton [4], this paper presents a theory based on non-stationary nonlinear dynamics of spherical gas bubbles and extends that 2007 paper to include liquid compressibility and thermal damping effects. The paper then shows how that nonlinear formulation can be reduced to the linear limit, and derives the expressions for the damping coefficients, the scattering cross section, the speed of sound and the attenuation, and compares these with the A&H theory. The current formulation has certain advantages over A&H theory such as implementing an energy conservation based nonlinear model for the gas pressure inside the bubble, having no sign ambiguity for the speed of sound formula (which is important when estimating the bubble void fraction) and correcting the ambiguity on the expression for scattering cross section, as identified in the recent work of Ainslie and Leighton [5]. Moreover, the theory presented here forms a basis for a nonlinear, time-dependent acoustic estimation model for gas bubble distributions in viscoelastic mediums since it avoids the commonly encountered assumptions on the bubble dynamics such as linearity, steady-state behaviour and monochromaticity.

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More information

Published date: June 2014
Venue - Dates: 2nd International Conference and Exhibition on Underwater Acoustics (UA2014), Greece, 2014-06-22 - 2014-06-27
Keywords: gassy sediments, nonlinear propagation, acoustic scattering
Organisations: Inst. Sound & Vibration Research

Identifiers

Local EPrints ID: 369561
URI: http://eprints.soton.ac.uk/id/eprint/369561
PURE UUID: b120ae87-6ea1-4142-a54f-ee3401e0347a
ORCID for T.G. Leighton: ORCID iD orcid.org/0000-0002-1649-8750
ORCID for P.R. White: ORCID iD orcid.org/0000-0002-4787-8713

Catalogue record

Date deposited: 30 Sep 2014 13:38
Last modified: 06 Jun 2018 13:12

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