1989 Fiscal Year Final Research Report Summary
Studies on the formation of wave groups and solitons in shallow water
| Project/Area Number |
62302045
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
TSUCHIYA Yoshito Professor, Disaster Prevention Research Institute, Kyoto University, 防災研究所, 教授 (90025883)
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| Co-Investigator(Kenkyū-buntansha) |
ISOBE Masahiko Associate Professor, Faculty of Engineering, University of Tokyo, 工学部, 助教授 (20114374)
YASUDA Takashi Professor, Faculty of Engineering, Gifu University, 工学部, 教授 (10093329)
YAMASHITA Takao Instructor, Disaster Prevention Research Institute, Kyoto University, 防災研究所, 助手 (30111983)
MASE Hajime Instructor, Faculty of Engineering, Kyoto University, 工学部, 助手 (30127138)
IWAGAKI Yuichi Professor, Faculty of Science & Engineering, Meijo University, 理工学部, 教授 (90027201)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Waves in shallow water / Wave group / soliton / Schroedinger equation / Random wave / Wave run / Directional spectrum |
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| Research Abstract |
In this study, the formation of wave groups and solitons in shallow water was investigated. The main results are; 1) In the transformation process of wave group structure, wave group becomes predominant due to narrow wave energy spectra, but in the developing stage it becomes week. The wave group formation process was investigated by the nonlinear Schroedinger equation. It was shown through the numerical simulation that in the wave propagation in the shallow water the wave group becomes flat to pretend soliton fission. 2) The equation of random waves propagating from deep to shalom-water was derived. It was shown by this equation that the wave group formation is made by wave modulation instability in Fourier mode and in the very shallow region the wave group fluctuates in the propagation. A statistical theory of random soliton train was proposed based on the conservative property of the eigenvalues of solitons. 3) In order to evaluate the influence of wave grouping on the directional wave spectra, a standard estimation method of directional spectra was proposed. Deformation of directional wave spectra by wave grouping was investigated by taking into account the carrier wave properties in wave group velocity.
Based on the above formation processes of wave groups and solitons the structure of waves in shallow water was considered.
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