Parabolic equation solutions with increased capabilities for layered poro-elastic media.

Metzler, Adam M.; Siegmann, William L.

doi:10.1121/1.3508896

“…However, it is possible for accuracy to deteriorate unacceptably for two-layer sediments, as shown in the top right panel. This dilemma prompted a full reexamination of formulations for poro-elastic media, with the result that a new set of variables was devised for layered and range-dependent environments [7]. The middle panel shows calculations for a range-independent environment with the revised formulation (denoted by q � ), along with a benchmark solution from the wavenumber integration code OASIS.…”

Section: Results (From Two Selected Investigations)mentioning

confidence: 99%

“…• Propagation variables and computational techniques, developed for elastic sediments and designed for range-dependent layered environments, are generalized to multi-layered poroelastic sediments [7], for which computational results agree with benchmarks for rangeindependent cases.…”

Section: Work Completedmentioning

confidence: 99%

Shallow Water Propagation

Siegmann¹,

McMahon²

2012

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LONG-TERM GOALSDevelop methods for deterministic and stochastic acoustic calculations in complex shallow water environments, specify their capabilities and accuracy, and apply them to explain experimental data and understand physical mechanisms of propagation. OBJECTIVES(A) Treat propagation from narrowband and broadband sources over elastic and poro-elastic sediments, and incorporate realistic bathymetric, topographic, and geoacoustic variations. (B) Construct representations for ocean environmental and geoacoustic variability using data and parametric models. Determine acoustic fields with PE, normal mode, and other approximation methods. Use experimental data and computational results to assess propagation mechanisms.

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“…Rensselaer Polytechnic Institute,110 Eighth Street,Jonsson-Rowland Science Center 1C08,Troy,NY,12180-3590 8. PERFORMING ORGANIZATION REPORT NUMBER…”

Section: Performing Organization Name(s) and Address(es)mentioning

confidence: 99%

“…• A new method for poro-elastic media is constructed [8], based on the variable reformulation in [5], to treat range dependence efficiently and accurately, and initial benchmarking of the implementation is demonstrated.…”

Section: Work Completedmentioning

confidence: 99%

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Shallow Water Propagation

Siegmann¹,

Metzler²,

McMahon³

2010

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LONG-TERM GOALSDevelop methods for deterministic and stochastic acoustic calculations in complex shallow water environments, specify their capabilities and accuracy, and apply them to understand experimental data and physical mechanisms of propagation. OBJECTIVES(A) Treat propagation from narrowband and broadband sources over elastic and poro-elastic sediments, and incorporate realistic bathymetric, topographic, and geoacoustic variations.(B) Quantify acoustic interactions with physical features in the ocean volume and with geoacoustic features of the ocean sediment, and analyze and interpret experimental data. APPROACH(A) Develop efficient and accurate parabolic equation (PE) techniques for propagation through heterogeneous sediments. Treat range dependence and sediment layering by single scattering and energy conservation methods. Benchmark results using data and special high-accuracy solutions.(B) Construct representations for ocean environmental and geoacoustic variability using data and parametric models. Determine acoustic fields with PE, normal mode, and approximation methods. Use experimental data and computational results to assess propagation mechanisms.

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Shallow Water Propagation

Siegmann¹

2010

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During the performance period, six students received their PhD degrees from Rensselaer Polytechnic Institute with ONR support, and their initial and current positions are provided in Section IV. Twenty-one papers were published, including ten in the Journal of the Acoustical Society of America and six in IEEE publications, and their references are listed in Section V. Thirty-six professional presentations were made, including thirty-two at national or international meetings, and their titles and venues are given in Section VI. Some research results and figures from the performance period are highlighted in Sections II and III. II. RESEARCH HIGHLIGHTS A. Propagation Model Development and Applications• Layered elastic sediments are important in shallow water and must be accurately handled as the basis for extensions to more complicated bottoms that include range dependence, poro-elasticity, and other physical mechanisms. Our parabolic equation formulation [1] resolved this task by using new choices of dependent variables, along with the same efficient and reliable numerical schemes as for fluid bottom models. The formulation accommodates all physical conditions at layer interfaces and avoids stability difficulties that arise in other approaches. Figure 1 illustrates results from our implementation. Comparing the upper and middle contour plots, we conclude that significant transmission level differences can occur in the ocean as a result of the elastic bottom waveguide. The lower contour plot demonstrates that this method, unlike other parabolic equations, can treat seismic sources. 20100308162

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Parabolic equation solutions with increased capabilities for layered poro-elastic media.

Cited by 4 publications

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Shallow Water Propagation

Shallow Water Propagation

Shallow Water Propagation

Shallow Water Propagation

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