An approximation to the three-dimensional parabolic-equation method for acoustic propagation

Perkins, John H.; Baer, Ralph N.

doi:10.1121/1.388032

Cited by 71 publications

(24 citation statements)

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“…Relying on wave guide propagation mechanisms, the second approximations open into modes solutions. Assuming extra constraints (specific stratification), the modes equation may become parabolic (Brekhovskikh & Lysanov, 1982) or using Perkins model, admit trigonometric function based solutions (Perkins & Baer, 1982). Green functions may also be introduced leading to Fourier transforms (Harrison, 1989).…”

Section: Requirements For Simulating Realistic Sonar Datamentioning

confidence: 99%

Sonar Data Simulation

Guériot¹,

Sintes²

2011

Sonar Systems

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Section: Requirements For Simulating Realistic Sonar Datamentioning

confidence: 99%

Sonar Data Simulation

Guériot¹,

Sintes²

2011

Sonar Systems

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“…mode/parabolic equation hybrid model described above, modal amplitudes were calculated by N×2D models, 35 which neglect out-of-plane effects by applying a 2D model to predict TL for vertical slices through the environment. Also, adiabatic-mode models, which neglect the effect of mode-coupling, were applied.…”

Section: Modal Amplitude Effectsmentioning

confidence: 99%

Normal Mode Analysis of Three-Dimensional Propagation Over a Small-Slope Cosine Shaped Hill

2015

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Three-dimensional propagation over an infinitely long cosine shaped hill is examined using an approximate normal mode/parabolic equation hybrid model that includes mode coupling in the out-going direction. The slope of the hill is relatively shallow, but it is significant enough to produce both mode-coupling and horizontal refraction effects. In the first part of the paper, the modeling approach is described, and the solution is compared to results obtained with a finite element method to evaluate the accuracy of the solution in light of assumptions made in formulating the model. Then the calculated transmission loss is interpreted in terms of a modal decomposition of the field, and the solution from the hybrid model is compared to adiabatic and N × 2D solutions to assess the relative importance of horizontal refraction and mode-coupling effects. An analysis using a horizontal ray trace is presented to explain differences in the modal interference pattern observed between the 3D and N × 2D solutions. The detailed discussion provides a thorough explanation of the observed 3D propagation effects and demonstrates the usefulness of the approximate normal mode/parabolic equation hybrid model as a tool to understand measured transmission loss in complex environments.

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“…Perkins and Baer [16] introduced the N ×2D approach to solve N two-dimensional problems, one for each of N vertical planes passing through the point source, and combine the results to form an approximate 3D solution. In their work [16], parabolic-equation programs are applied to solve each two-dimensional problem.…”

Section: The N ×2d Seamount Modelmentioning

confidence: 99%

Three-dimensional propagation and scattering around a conical seamount

Luo

Schmidt

2009

The Journal of the Acoustical Society of America

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In this thesis, a numerically efficient three-dimensional propagation and scattering model is developed based on the three-dimensional coupled mode theory for axisymmetric bathymetry. The three-dimensional coupled mode approach applied in this thesis is fundamentally identical to the one applied in earlier models, such as the one presented by Taroudakis [20]. Thus, it is based on a Fourier expansion of the acoustic field around a seamount, with each azimuthal expansion coefficient being represented by a two-way coupled mode formulation. However, earlier formulations were severely limited in terms of frequency, size and geometry of the seamount, the seabed composition, and the distance between the source and the seamount, and are totally inadequate for modeling high-frequency, large-scale seamount problems. By introducing a number of changes in the numerical formulation and using a standard normal mode model (C-SNAP) for determining the fundamental modal solutions and coupling coefficients, orders of magnitude improvement in efficiency and fidelity has been achieved, allowing for realistic propagation and scattering scenarios to be modeled, including effects of seamount roughness and realistic sedimentary structure. Also, by the simple superposition principle, the computational requirements are made independent of the distance between the seamount and the source and receivers, and dependent only on the geometry of the seamount and the frequency of the source.First, this thesis investigates the scattering from a cylindrical island, which is the simplest case of a conical seamount problem. Our model, using the superposition method, can solve the cylindrical problem in Athanassoulis and Prospathopoulos's paper [3] with the same accuracy while saving about 4/5 computational effort.Second, this thesis demonstrates the spectral coupled mode approach, which includes a two-way coupled mode model and a superposition representation of the field.Third, this thesis applies the three-dimensional model to investigate some physics issues of three-dimensional seamount scattering. As a result of the investigation, we learn that the N ×2D model is a poor approximation of the true three-dimensional model when the three-dimensional effects are significant, though it is a good approximation of the three-dimensional model otherwise. The convergence of the model in 3 terms of the seamount discretization is also discussed and demonstrated.Finally, our three-dimensional spectral coupled mode model is tested by the application of the Kermit Seamount problem with realistic ocean environmental data from the 2004 BASSEX experiment.

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An approximation to the three-dimensional parabolic-equation method for acoustic propagation

Cited by 71 publications

References 0 publications

Sonar Data Simulation

Sonar Data Simulation

Normal Mode Analysis of Three-Dimensional Propagation Over a Small-Slope Cosine Shaped Hill

Three-dimensional propagation and scattering around a conical seamount

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