Sound absorption in sea water

Fisher, F. H.; Simmons, V. P.

doi:10.1121/1.2015423

Cited by 41 publications

(49 citation statements)

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“…1c). Under the pressure of sound waves the relaxation mechanism is a chemical association-dissociation reaction [15] giving rise to a large volume change upon ionization ( [21]. As the temperature increases a decrease of both the partial molal volume change ( V * ) and the partial molal compressibility ( * ) occurs ( Table 3).…”

Section: Viscosity Ratiomentioning

confidence: 99%

Ocean Ultrasonic Shear and Compression Viscosities

Alemán¹,

Sangrà²,

Carbó³

2009

TOACOJ

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A comprehensive description of ocean molecular flow and deformation is provided with the help of hydrodynamic and ultrasonic principles. Hydrodynamic computation of true or natural viscosities shows that ocean shear viscosity ( G ), compression viscosity ( K ), and extensional viscosity ( E ) are interrelated. There are no experimental methods available for the in situ measurement of these viscosities. Sound absorption coefficients ( obs ) allow to know the ultrasonic shear ( UG ), compression ( UK ), and longitudinal ( L ) viscosities, which decrease with increasing frequency and increase with increasing temperature, the flow activation energies having nearly equivalent values; pressure (depth) increase/decrease them at low/high frequencies. The viscosities * UG , * UK , * L are approached at about 1000 KHz. They decrease with temperature and pressure, and increase with salinity. The * UG becomes equal to the true shear viscosity G at the viscosity ratio = UK / UG = 0.

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Section: Viscosity Ratiomentioning

confidence: 99%

Ocean Ultrasonic Shear and Compression Viscosities

Alemán¹,

Sangrà²,

Carbó³

2009

TOACOJ

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“…수층에서의 감쇠계수는 문헌들에 보고 된 감쇠계수 모델로부터 쉽게 계산할 수 있으 며, [11,12] [14] 이 제안한 모 델을 기초로 한 모델을 제시하였다. 원거리에서 후방산란강도를 구하는 소나 방정식 은 식(3)과 같이 표현된다.…”

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5-MHz Volume Backscattering Strength Measurements from Suspended Sediment Concentrations

Lee¹,

Choi

2013

The Journal of the Acoustical Society of Korea

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ABSTRACT:The erosion, suspension, and transport of sediment frequently occur in the coastal waters and estuarine. These processes often generate the so-called fluid mud layer, which is defined as a high-concentration aqueous suspension of fine grained sediment (> 10 g/l), consisting mainly of silt and clay-size particles. Therefore the high-resolution ultrasound is mostly used to detect or monitor the fluid mud layer. Because the sound attenuation tends to increase rapidly with the suspended sediment concentration, it is necessary to consider the accurate attenuation correction to estimate the backscattering strengths from the suspended sediment layers. In this paper, the volume backscattering strengths with various suspended sediment concentrations were measured using 5-MHz ultrasound signal in a small-scale water tank. The sound attenuation due to the viscosity and scattering from suspended sediment particles was predicted by the Richard's model and applied to the sonar equation to estimate the volume backscattering strengths from the suspended sediment concentrations. For the case that the additional attenuation was not considered, the volume backscattering strengths increased to the concentration of 20 g/l, and over this point, the backscattering strengths were roughly constant. However, for the case that the attenuation due to the suspended sediment concentration was considered, the backscattering strengths increased with the concentration.

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“…The value of pH can vary with the depth and also vary significantly from ocean to ocean at deeper depths [8][9][10][11]. At the surface, however, pH-values tend to be uniform due to the contact with the well-mixed atmosphere, and are usually the highest in the water column (typically pH > 8.3) [12].…”

Section: Attenuation Loss Models -------------Mechanism --------mentioning

confidence: 99%

Revisions to an empirical surface loss model using a correction for pH-dependent attenuation

Christian

Browning

Williams

1994

The Journal of the Acoustical Society of America

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Empirically derived surface loss values are not obtained directly but are derived from propagation loss measurements that include at least two other components. Surface loss is determined by making assumptions with regard to spreading loss, volume attenuation (and bottom loss, if appropriate). Marsh and Schulkin [AVCO Marine Electronics Office Tech. Rep. (1962)] analyzed an extensive set of transmission loss data from surface duct propagation to obtain surface loss values. They assumed that attenuation was entirely due to magnesium sulfate and used the early Marsh–Schulkin [J. Brit. IRE 25, N6 (1963)] attenuation formula (Thorp, Mellen et al., and Francois Garrison attenuation formulas were not known at the time). Corrections to the Marsh–Schulkin surface loss data have been computed that account for the differences between the Marsh–Schulkin and Mellen et al. [NUSC TR 7293 (1983)] attenuation formulae. The revised values show less loss for all frequency-wave-height (F-H) products. The Kuo [J. Acoust. Soc. Am. 36 (1964)] perturbation theory estimates of surface loss are shown to be in good agreement with the revised data at low F-H products.

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Sound absorption in sea water

Cited by 41 publications

References 0 publications

Ocean Ultrasonic Shear and Compression Viscosities

Ocean Ultrasonic Shear and Compression Viscosities

5-MHz Volume Backscattering Strength Measurements from Suspended Sediment Concentrations

Revisions to an empirical surface loss model using a correction for pH-dependent attenuation

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