Internal mechanism of giant waves in multidirectional irregular waves and estimation of their impact forces

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02369
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: Hiroshima University
• Principal Investigator: Mutsuda Hidemi 広島大学, 先進理工系科学研究科(工), 教授 (80273126)
• Co-Investigator(Kenkyū-buntansha): 田中 義和 広島大学, 先進理工系科学研究科(工), 准教授 (00335704) ; 谷口 直和 広島大学, 工学研究院, 研究員 (30711733)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 海洋巨大波 / 洋上風力発電施設 / 粒子法 / Draupner Wave / Freak Wave / 砕波 / 浮体構造物

Outline of Final Research Achievements

A numerical design tool that takes into account large tsunamis and extreme waves (Freak waves, triangular waves, Draupner waves, etc.) that occur near Japan is necessary, and it is important to estimate exciting force and 6DoF motions of ocean structures. The purpose of this study is to elucidate the generation/development mechanism, wave breaking/attenuation mechanism of giant waves generated in multi-directional irregular waves in real sea states from a physical and engineering point of view. This study focused on, (1) Estimation of exciting wave loads of giant waves acting on a moored floating structure, (2) Breaking and emergence prediction of giant waves, (3) Rational calculation of impact loads caused by giant waves, (4) Prediction and risk assessment of encounters with giant waves that hinder the management and operation of offshore structures were investigated.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

我が国近海で発生する大津波や極限波浪（Freak wave，三角波，Draupner waveなど）を考慮した設計ツールは必要不可欠であり，それに基づく合理的な設計値を推定することが重要である．本研究成果は，多方向不規則波群によって発生する砕波を伴うDraupner Waveに着目して，その発生・発達・砕波・減衰機構，さらには砕波形式による物理機構の比較を行っており，学術的意義は非常に高い．また，海洋巨大波に関わる海洋工学，海岸工学，船舶工学，海洋物理学分野の学理研究の飛躍的な進歩に繋がるため，海難事故の防災・減災，人命保護，各種海洋構造物の管理運用等の社会的要請に応えるものである．