Forward and specular scattering from a rough surface: theory and experiment

Boyd, Michael L.; Deavenport, R. L.

doi:10.1121/1.1913394

Cited by 18 publications

(6 citation statements)

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“…(5) is the pressure p 0 scattered (reflected) by an infinite, pressure-release plane surface and is given by the image solution. 4,6 Since the ensemble average yields a constant, the differentiation of this term is zero, thus eliminating the slope dependence in the average scattered pressure. For the scattered intensity, the ensemble average yields…”

Section: Slope Approximations In the Scattering Integralsmentioning

confidence: 98%

Comparison of slope approximations used in rough surface scattering

Welton

2015

The Journal of the Acoustical Society of America

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Two widely used surface slope approximations are compared to an initially exact method that treats the slopes via a differential operator acting on the characteristic function. The differential operator treatment ceases to be exact when the integrand in the scattering integrals is approximated using a Gaussian directivity approximation and Fresnel phase approximation. Analysis is restricted to the Kirchhoff approximation (single scattering). One of the simpler slope approximations agrees with the more comprehensive differential operator approximation for all backscattering geometries, as well as for specular scattering geometries down to grazing angles comparable to the source beamwidth.

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Section: Slope Approximations In the Scattering Integralsmentioning

confidence: 98%

Comparison of slope approximations used in rough surface scattering

Welton

2015

The Journal of the Acoustical Society of America

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“…The Kirchhoff approximation [40]- [52] has been widely studied, and was used in all of the coherence studies [1]- [20] and most of the scattering studies [21], [23]- [31], [35], [37], [38] cited in the Introduction. Here it will be assumed that the Kirchhoff approximation is valid when the surface slopes are not too steep.…”

Section: A the Kirchhoff Approximationmentioning

confidence: 99%

Cross Correlation of Omnidirectional, Broadband Signals Scattered by a Random Pressure-Release Surface

Welton

2015

IEEE J. Oceanic Eng.

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Expressions for the cross correlation of omnidirectional, broadband continuous-wave (CW) acoustic signals scattered by a pressure-release random surface are derived for both vertically and horizontally spaced hydrophones using the Kirchhoff approximation for the boundary values and the Fresnel phase approximation. The resulting expressions for the spatial coherence are simple in form and require no approximations in the description of the random surface. As the surface becomes perfectly smooth, the expressions reduce to the image solution, thus ensuring the proper limiting behavior. Two narrowband models for vertical coherence were compared to experimental data collected during a sea test at the frequencies of 14, 16, 18, and 20 kHz with a maximum hydrophone spacing of 1.4 m. One model used the measured sound-speed profile (SSP) to estimate input parameters, and the other model assumed isospeed conditions. The agreement between the experimental data and the model based on the measured SSP is very good, and the agreement with the isospeed model is almost as good.

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“…1(c). Although there are many theoretical studies on ultrasonic wave scattering from rough surfaces, [29][30][31][32][33][34] the Kirchhoff theory is widely used for investigating the scattering phenomena because of its comprehensible physical basis and relatively simple analytical expression for the scattered ultrasonic field. Using the Kirchhoff theory under some assumptions, such as plane wave incidence, a single scattering event, Gaussian distribution of surface height, Gaussian correlation function of surface height, and far field conditions, the scattered field can be considered to be a superposition of coherent and diffuse components.…”

Section: Scattered Ultrasonic Waves From Rough Surfacesmentioning

confidence: 99%

Surface Roughness Characterization through the Use of Diffuse Component of Scattered Air-Coupled Ultrasound

Sukmana

Ihara

2006

jjap

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Surface roughness characterization through the use of diffuse component of scattered air-coupled ultrasound is presented in this paper. Ultrasonic measurements using broadband air-coupled capacitance transducers with a center frequency of 0.5 MHz have been performed on several specimens with different rms roughness Rq and surface correlation length λ0 from 0.04 to 244.1 µm and from 29 to 445 µm, respectively. The diffuse components of the scattered ultrasonic waves from the specimens were measured at various scattering angles. It has been shown that the amplitude of diffuse component significantly changes with both the roughness Rq and the surface correlation length λ0 of the specimen. In order to examine the behavior of the amplitude, the measured results were compared with theoretical ones calculated from a Kirchhoff-based scattering model.

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Forward and specular scattering from a rough surface: theory and experiment

Cited by 18 publications

References 0 publications

Comparison of slope approximations used in rough surface scattering

Comparison of slope approximations used in rough surface scattering

Cross Correlation of Omnidirectional, Broadband Signals Scattered by a Random Pressure-Release Surface

Surface Roughness Characterization through the Use of Diffuse Component of Scattered Air-Coupled Ultrasound

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