Pub Date : 2017-03-28DOI: 10.1142/S0218396X17500254
P. Langer, M. Maeder, C. Guist, M. Krause, S. Marburg
Choosing the right number and type of elements in modern commercial finite element tools is a challenging task. It requires a broad knowledge about the theory behind or much experience by the user. Benchmark tests are a common method to prove the element performance against analytical solutions. However, these tests often analyze the performance only for single elements. When investigating the complete mesh of an arbitrary structure, the comparison of the element’s performance is quite challenging due to the lack of closed or fully converged solutions. The purpose of this paper is to show a high-precision comparison of eigenfrequencies of a real structure between experimental and numerical results in the context of an element performance check with respect to a converged solution. Additionally, the authors identify the practically relevant accuracy of simulation and experiment. Finally, the influence of accuracy with respect to the number of elements per standing structural bending wave is shown.
{"title":"More Than Six Elements Per Wavelength: The Practical Use of Structural Finite Element Models and Their Accuracy in Comparison with Experimental Results","authors":"P. Langer, M. Maeder, C. Guist, M. Krause, S. Marburg","doi":"10.1142/S0218396X17500254","DOIUrl":"https://doi.org/10.1142/S0218396X17500254","url":null,"abstract":"Choosing the right number and type of elements in modern commercial finite element tools is a challenging task. It requires a broad knowledge about the theory behind or much experience by the user. Benchmark tests are a common method to prove the element performance against analytical solutions. However, these tests often analyze the performance only for single elements. When investigating the complete mesh of an arbitrary structure, the comparison of the element’s performance is quite challenging due to the lack of closed or fully converged solutions. The purpose of this paper is to show a high-precision comparison of eigenfrequencies of a real structure between experimental and numerical results in the context of an element performance check with respect to a converged solution. Additionally, the authors identify the practically relevant accuracy of simulation and experiment. Finally, the influence of accuracy with respect to the number of elements per standing structural bending wave is shown.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750025"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500254","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43737463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X16300012
Seongkyu Lee
This paper reviews the equivalent source method (ESM), an attractive alternative to the standard boundary element method (BEM). The ESM has been developed under different names: method of fundamental solutions, wave superposition method, equivalent source method, etc. However, regardless of the method name, the basic concept is very similar; that is to use auxiliary points called equivalent sources to reconstruct the acoustic pressure for radiation or scattering problems. The strength of the equivalent sources are then determined via various approaches such that the boundary conditions on the boundary surface are satisfied. This paper reviews several frequency-domain and time-domain ESMs. There are several distinct advantages in these types of methods: (1) the method is a meshless approach so that it is easy and simple to implement; (2) it does not have a numerical singularity problem that occurs in the BEM; (3) the number of equivalent sources can be fewer than the number of surface collocation points so that the matrix size is reduced and a fast computation is achieved for large problems. The main issue of the ESM is that there is no rule to find out the optimal number and position of equivalent sources. In addition, the ESM suffers from the numerical instability that is associated with the ill-conditioned matrix. Some guidelines have been suggested in terms of finding the number and position of the sources, and several numerical techniques have been developed to resolve the numerical instability. This paper reviews the common theories, numerical issues and challenges of the ESM, and it summarizes recent developments and applications of the ESM to aircraft noise.
{"title":"Review: The Use of Equivalent Source Method in Computational Acoustics","authors":"Seongkyu Lee","doi":"10.1142/S0218396X16300012","DOIUrl":"https://doi.org/10.1142/S0218396X16300012","url":null,"abstract":"This paper reviews the equivalent source method (ESM), an attractive alternative to the standard boundary element method (BEM). The ESM has been developed under different names: method of fundamental solutions, wave superposition method, equivalent source method, etc. However, regardless of the method name, the basic concept is very similar; that is to use auxiliary points called equivalent sources to reconstruct the acoustic pressure for radiation or scattering problems. The strength of the equivalent sources are then determined via various approaches such that the boundary conditions on the boundary surface are satisfied. This paper reviews several frequency-domain and time-domain ESMs. There are several distinct advantages in these types of methods: (1) the method is a meshless approach so that it is easy and simple to implement; (2) it does not have a numerical singularity problem that occurs in the BEM; (3) the number of equivalent sources can be fewer than the number of surface collocation points so that the matrix size is reduced and a fast computation is achieved for large problems. The main issue of the ESM is that there is no rule to find out the optimal number and position of equivalent sources. In addition, the ESM suffers from the numerical instability that is associated with the ill-conditioned matrix. Some guidelines have been suggested in terms of finding the number and position of the sources, and several numerical techniques have been developed to resolve the numerical instability. This paper reviews the common theories, numerical issues and challenges of the ESM, and it summarizes recent developments and applications of the ESM to aircraft noise.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1630001"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X16300012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45821387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X17500047
Hong-sheng Gao, Sheng Li
This paper is concerned with the problem of obtaining a unique solution for radiation at irregular frequencies when an integral equation of frequency averaged quadratic pressure (FAQP) is used to get robust predictions at medium and high frequencies. It is proved that there is no unique solution of the integral equation of FAQP at irregular frequencies, and existence and uniqueness of solutions under four types of boundary conditions are discussed. A combined energy boundary integral equation formulation (CEBIEF) is presented and proves to be efficient to overcome the nonuniqueness of the integral equation of FAQP. The numerical examples are given to demonstrate the versatility of the CEBIEF method with a proposed function correctly indicating a solution.
{"title":"Improved Integral Formulation for Acoustic Radiation Using Integral Equation of Frequency Averaged Quadratic Pressure","authors":"Hong-sheng Gao, Sheng Li","doi":"10.1142/S0218396X17500047","DOIUrl":"https://doi.org/10.1142/S0218396X17500047","url":null,"abstract":"This paper is concerned with the problem of obtaining a unique solution for radiation at irregular frequencies when an integral equation of frequency averaged quadratic pressure (FAQP) is used to get robust predictions at medium and high frequencies. It is proved that there is no unique solution of the integral equation of FAQP at irregular frequencies, and existence and uniqueness of solutions under four types of boundary conditions are discussed. A combined energy boundary integral equation formulation (CEBIEF) is presented and proves to be efficient to overcome the nonuniqueness of the integral equation of FAQP. The numerical examples are given to demonstrate the versatility of the CEBIEF method with a proposed function correctly indicating a solution.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750004"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500047","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47467261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X1650017X
Ersen Arslan, Yusuf Özyörük, M. Çaliskan
In this paper sound propagation through an air-filled circular duct containing water droplets has been studied by solving numerically one-dimensional linearized Euler equations in frequency domain. Interactions between the liquid and gas phases were accounted for by proper source terms. Waves were introduced into the domain via Perfectly Matched Layers (PML) equations applied in finite regions adjacent to the truncated ends of the duct. Absorption and dispersion results due to energy transfer from air to the water droplets were obtained as a function of average droplet diameter and droplet concentration as well as finite mass loading. Results agree well with those available in the literature.
{"title":"Numerical Analysis of One-Dimensional Sound Propagation Through a Duct Containing Water Droplets","authors":"Ersen Arslan, Yusuf Özyörük, M. Çaliskan","doi":"10.1142/S0218396X1650017X","DOIUrl":"https://doi.org/10.1142/S0218396X1650017X","url":null,"abstract":"In this paper sound propagation through an air-filled circular duct containing water droplets has been studied by solving numerically one-dimensional linearized Euler equations in frequency domain. Interactions between the liquid and gas phases were accounted for by proper source terms. Waves were introduced into the domain via Perfectly Matched Layers (PML) equations applied in finite regions adjacent to the truncated ends of the duct. Absorption and dispersion results due to energy transfer from air to the water droplets were obtained as a function of average droplet diameter and droplet concentration as well as finite mass loading. Results agree well with those available in the literature.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1650017"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X1650017X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47065820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X16500211
Chuanxiu Xu, S. Piao, Shie Yang, Haigang Zhang, Li Li
In ocean waveguides, the ocean bottom is usually approximated as a half-space. Thus, there exist no reflection waves at the half-space bottom and condition of radiation at infinity should be satisfied. In numerical solutions like parabolic equation methods, the depth domain has to be truncated, which can generate reflection waves from the truncated ocean bottom. To reduce the effect of reflection waves and to simulate an unbounded ocean bottom accurately, an artificial absorbing layer (ABL) was used. As was demonstrated, an ABL meets well the demand of accuracy in sound field calculation. However, both the sea-bottom layer and the artificial absorbing layer are needed to be set quite thick by using an ABL technique. Fortunately, a PML with several wavelengths can keep similar calculation accuracy with an ABL with dozens of wavelengths. In this paper, perfectly matched layer (PML) techniques for three parabolic equation (PE) models RAM, RAMS and a three-dimensional PE model in underwater acoustics are presented. A key technique of PML “complex coordinate stretching” is used to truncate unbounded domains and to simulate infinity radiation conditions instead of the ABL in those models. The numerical results illustrate that the PML technique is of higher efficiency than the ABL technique at truncating the infinity domain with minimal spurious reflections in PE models.
{"title":"This Submission is for Special Issue on Underwater Acoustics: Perfectly Matched Layer Technique for Parabolic Equation Models in Ocean Acoustics","authors":"Chuanxiu Xu, S. Piao, Shie Yang, Haigang Zhang, Li Li","doi":"10.1142/S0218396X16500211","DOIUrl":"https://doi.org/10.1142/S0218396X16500211","url":null,"abstract":"In ocean waveguides, the ocean bottom is usually approximated as a half-space. Thus, there exist no reflection waves at the half-space bottom and condition of radiation at infinity should be satisfied. In numerical solutions like parabolic equation methods, the depth domain has to be truncated, which can generate reflection waves from the truncated ocean bottom. To reduce the effect of reflection waves and to simulate an unbounded ocean bottom accurately, an artificial absorbing layer (ABL) was used. As was demonstrated, an ABL meets well the demand of accuracy in sound field calculation. However, both the sea-bottom layer and the artificial absorbing layer are needed to be set quite thick by using an ABL technique. Fortunately, a PML with several wavelengths can keep similar calculation accuracy with an ABL with dozens of wavelengths. In this paper, perfectly matched layer (PML) techniques for three parabolic equation (PE) models RAM, RAMS and a three-dimensional PE model in underwater acoustics are presented. A key technique of PML “complex coordinate stretching” is used to truncate unbounded domains and to simulate infinity radiation conditions instead of the ABL in those models. The numerical results illustrate that the PML technique is of higher efficiency than the ABL technique at truncating the infinity domain with minimal spurious reflections in PE models.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1650021"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X16500211","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43326971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X17500035
Leilei Chen, S. Marburg, Haibo Chen, Hao Zhang, H. Gao
Full interaction between structural and fluid domains must be considered for light structures immersed in heavy fluid (e.g. thin steel shells in water). The structural-acoustic design sensitivity analysis provides information on the effect of the design variable on acoustic performance, which makes it a key step for noise control and structural-acoustic optimization. This study uses the finite element method (FEM) to model the structure domain, while the fast multipole boundary element method (BEM) is applied to the exterior acoustic domain. An adjoint operator approach is developed to calculate the sensitivity of the radiated sound power with respect to the design variables, which can be any structural or fluid parameter (e.g. fluid or structural density, Poisson’s ratio, Young’s modulus, and geometric measures). Numerical examples are presented to demonstrate the validity and efficiency of the proposed algorithm.
{"title":"An Adjoint Operator Approach for Sensitivity Analysis of Radiated Sound Power in Fully Coupled Structural-Acoustic Systems","authors":"Leilei Chen, S. Marburg, Haibo Chen, Hao Zhang, H. Gao","doi":"10.1142/S0218396X17500035","DOIUrl":"https://doi.org/10.1142/S0218396X17500035","url":null,"abstract":"Full interaction between structural and fluid domains must be considered for light structures immersed in heavy fluid (e.g. thin steel shells in water). The structural-acoustic design sensitivity analysis provides information on the effect of the design variable on acoustic performance, which makes it a key step for noise control and structural-acoustic optimization. This study uses the finite element method (FEM) to model the structure domain, while the fast multipole boundary element method (BEM) is applied to the exterior acoustic domain. An adjoint operator approach is developed to calculate the sensitivity of the radiated sound power with respect to the design variables, which can be any structural or fluid parameter (e.g. fluid or structural density, Poisson’s ratio, Young’s modulus, and geometric measures). Numerical examples are presented to demonstrate the validity and efficiency of the proposed algorithm.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750003"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48824973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-28DOI: 10.1142/S0218396X17500072
O. Soboleva
The effective coefficients for the problem of propagation of acoustic waves in multifractal elastic media using the subgrid modeling approach are obtained. The maximum scale of heterogeneities of the medium in question is assumed to be small as compared with the wavelength. If a isotropic medium is assumed to satisfy the improved Kolmogorov similarity hypothesis, the term for the effective coefficient of the elastic stiffness coincides with the Landau–Lifshitz–Matheron formula. Both isotropic and anisotropic media are considered. The numerical testing for the wave propagating at a distance, which is of the same order as a typical wavelength of a source, illustrates the efficiency of the approach proposed.
{"title":"Modeling of Propagation of Antiplane Acoustic Waves in Multiscale Media with Lognormal Distribution of Parameters","authors":"O. Soboleva","doi":"10.1142/S0218396X17500072","DOIUrl":"https://doi.org/10.1142/S0218396X17500072","url":null,"abstract":"The effective coefficients for the problem of propagation of acoustic waves in multifractal elastic media using the subgrid modeling approach are obtained. The maximum scale of heterogeneities of the medium in question is assumed to be small as compared with the wavelength. If a isotropic medium is assumed to satisfy the improved Kolmogorov similarity hypothesis, the term for the effective coefficient of the elastic stiffness coincides with the Landau–Lifshitz–Matheron formula. Both isotropic and anisotropic media are considered. The numerical testing for the wave propagating at a distance, which is of the same order as a typical wavelength of a source, illustrates the efficiency of the approach proposed.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750007"},"PeriodicalIF":0.0,"publicationDate":"2017-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47448347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-27DOI: 10.1142/S0218396X17500266
Lin Su, Li Ma, Shengming Guo
The effect of sound speed profile (SSP) mismatch on source localization in shallow-water waveguides with a typical negative gradient (or thermocline) is studied numerically and experimentally. The results are interpreted using a normal mode model and a ray model. It is found that a matched-field processor is insensitive to SSP mismatch for sources above the thermocline. In addition, the sensitivity of the processor to SSP mismatch increases with the depth of sources above the thermocline.
{"title":"Influence of Sound Speed Profile on Source Localization at Different Depths","authors":"Lin Su, Li Ma, Shengming Guo","doi":"10.1142/S0218396X17500266","DOIUrl":"https://doi.org/10.1142/S0218396X17500266","url":null,"abstract":"The effect of sound speed profile (SSP) mismatch on source localization in shallow-water waveguides with a typical negative gradient (or thermocline) is studied numerically and experimentally. The results are interpreted using a normal mode model and a ray model. It is found that a matched-field processor is insensitive to SSP mismatch for sources above the thermocline. In addition, the sensitivity of the processor to SSP mismatch increases with the depth of sources above the thermocline.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750026"},"PeriodicalIF":0.0,"publicationDate":"2017-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500266","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42950042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-16DOI: 10.1142/S0218396X17500242
Jinfu Liang, Lun-Xun Gong
Two novel composite structures that couple a sonic crystal waveguide (SCW) to a self-collimating sonic crystal (SCSC) are proposed to control beam divergence and transmission. Finite element simulations indicate that an SCSC attached to the output of an SCW can reduce the half-power angular width by 48.81% and enhance the normal radiation intensity by 104.17%. This is due to both the high self-collimation properties and low interference of SCSCs. A composite consisting of four SCWs coupled via an SCSC exhibits high transmission with low cross talk when multiple signals are introduced. The proposed composites could be important in the SCW directional emission and SCW-based integrated circuit development.
{"title":"Enhanced Sound Beam from a Sonic Crystal Waveguide via a Self-Collimating Sonic Crystal","authors":"Jinfu Liang, Lun-Xun Gong","doi":"10.1142/S0218396X17500242","DOIUrl":"https://doi.org/10.1142/S0218396X17500242","url":null,"abstract":"Two novel composite structures that couple a sonic crystal waveguide (SCW) to a self-collimating sonic crystal (SCSC) are proposed to control beam divergence and transmission. Finite element simulations indicate that an SCSC attached to the output of an SCW can reduce the half-power angular width by 48.81% and enhance the normal radiation intensity by 104.17%. This is due to both the high self-collimation properties and low interference of SCSCs. A composite consisting of four SCWs coupled via an SCSC exhibits high transmission with low cross talk when multiple signals are introduced. The proposed composites could be important in the SCW directional emission and SCW-based integrated circuit development.","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"1 1","pages":"1750024"},"PeriodicalIF":0.0,"publicationDate":"2017-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500242","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49451707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-16DOI: 10.1142/S0218396X17500175
Bo Gao, Ning Wang, H. Wang
The effects of rough sea surface on the long-range bottom reverberation in shallow seas are studied by the coupled mode reverberation theory. The scattering effect caused by irregular rough sea surface is described by couple coefficients. The decaying rules of long-range bottom reverberation level are simulated at different sea states, and the rough sea surface effect on the coherence of distant bottom reverberation is also discussed. It is indicated that irregular upper boundary has changed the propagation effect of the shallow water waveguide, and bottom reverberation, which is dominated among other kinds of reverberation in shallow water, is affected by the sea surface scattering as the increasing sea state. Compared with other literatures, the emphasis of this paper is to present the mechanism of rough sea surface scattering by describing the transfer of energy between different modes, and the details of energy transitions between different modes which are caused by sea surface scattering are presente...
{"title":"Investigation of Sea Surface Effect on Shallow Water Reverberation by Coupled Mode Method","authors":"Bo Gao, Ning Wang, H. Wang","doi":"10.1142/S0218396X17500175","DOIUrl":"https://doi.org/10.1142/S0218396X17500175","url":null,"abstract":"The effects of rough sea surface on the long-range bottom reverberation in shallow seas are studied by the coupled mode reverberation theory. The scattering effect caused by irregular rough sea surface is described by couple coefficients. The decaying rules of long-range bottom reverberation level are simulated at different sea states, and the rough sea surface effect on the coherence of distant bottom reverberation is also discussed. It is indicated that irregular upper boundary has changed the propagation effect of the shallow water waveguide, and bottom reverberation, which is dominated among other kinds of reverberation in shallow water, is affected by the sea surface scattering as the increasing sea state. Compared with other literatures, the emphasis of this paper is to present the mechanism of rough sea surface scattering by describing the transfer of energy between different modes, and the details of energy transitions between different modes which are caused by sea surface scattering are presente...","PeriodicalId":54860,"journal":{"name":"Journal of Computational Acoustics","volume":"25 1","pages":"1750017"},"PeriodicalIF":0.0,"publicationDate":"2017-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S0218396X17500175","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48206479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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