Understanding the Mechanism of Freak Waves and Establishing a New Breaking Criterion in Multi-Directional Waves

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14429
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: Kyoto University
• Principal Investigator: Kanehira Taiga 京都大学, 防災研究所, 特定研究員 (50880019)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: 砕波 / 多方向波浪場 / 粒子法 / 数値シミュレーション

Outline of Final Research Achievements

Offshore areas where ships frequently navigate are rich in ocean energy resources and are essential for economic activities. For the further development of economic activities, it is necessary to establish breaking wave criterion and methods for estimating maximum wave forces in offshore multi-directional wave fields.

In this study, we experimentally obtained spatial waveforms of freak waves in bi-directional wave groups, allowing for the validation of numerical models of freak waves in multi-directional wave fields. Additionally, we developed a coupling model combining a potential calculation model, which solves large-scale wave fields, and a particle method, which resolves non-linear breaking phenomena in smaller regions. This approach reduces computational costs and enables the estimation of maximum wave forces on three-dimensional structures.However, challenges remain in achieving bidirectional coupling in multi-directional wave fields, which will be addressed in future research.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

海洋エネルギーの賦存量が多く経済活動に不可欠な場所である沖合の経済的利用が難しいのは、多方向波浪場において出現する海洋巨大波の最大波力推定手法が未確立なためだ。本研究では多方向波群における破波現象の高密度情報を実験的に取得。これにより、従来の一方向波浪場のみならず、多方向波浪場における数値計算モデルとの精度検証が可能となった。さらに、計算負荷を低減した数値計算モデルを開発し、３次元空間における海洋巨大波の最大波力推定が可能となった。今後、開発した数値計算技術によって、多方向波浪場における海洋巨大波の物理諸量の詳細が明らかになり、沖合の経済活動域の拡大に繋がると考えられる。