Numerical modeling of underwater sound propagation in the presence of triangle obstacles at low frequency

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• 作者：Saman Kermani ; Parviz Ghadimi
• 关键词：Underwater sound ; Triangle obstacle ; Parabolic equation ; Low frequency ; Implicit finite difference
• 刊名：Journal of the Brazilian Society of Mechanical Sciences and Engineering
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：39
• 期：3
• 页码：695-708
• 全文大小：
• 刊物主题：Mechanical Engineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1806-3691
• 卷排序：39

文摘

Low frequency sound propagation from industrial activities in underwater is considered immensely important by many scientists. For reducing the destructive effects of low frequency sound at long range, different obstacles can be placed in the direction of sound propagation. However, experimental analysis of this phenomenon is very complex. This is mainly due to the fact that oceans have non-homogeneous environments, while the presence of various sediments, animals, and geological phenomena add to the complexity. Accordingly, numerical models are considered good alternatives for underwater acoustic simulation. In the current study, parabolic equation method is applied for numerically analyzing sound propagation with low frequencies in the presence of triangle obstacles in different situations and arrangements. To accomplish this task, the implicit finite difference approach is adopted to solve the governing parabolic equation and a computer program is developed in Python language. Furthermore, Greene source and Claerbout estimations are applied to simulate wide angle sound propagation. The effects of various physical parameters such as sound speed profiles, source depth, and frequencies are investigated. Results of the analyses performed on the effects of object geometry indicate that triangle obstacle is more effective than the square obstacle for increasing the transmission loss (TL). Investigation of the effects of two sound speeds of Munk (Etter, Underwater acoustic modeling and simulation, Taylor & Francis, New York 2003) and linear profiles on transmission loss shows that Munk (Etter, Underwater acoustic modeling and simulation, Taylor & Francis, New York 2003) profile causes a spatial shift in TL compared to that of linear profile. On the other hand, the conducted study on three arrangements of single, triple and quintuple triangles at different distances, and frequencies indicate that values of TL in the case of triple triangle arrangement are lower than those by the other two triangle arrangements at different frequencies. Therefore, this arrangement is found to be inappropriate for mitigation of sound travel range. The results of parametric studies on the effects of source depth on TL demonstrate that peak of the TL graph for the receiver depth in vicinity of the free surface, in view of the deeper source, is much larger than those of the shallow source depth.