Development of a simple prediction model for vortex-induced motion of floating platforms with arbitrarily placed columns

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04496
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: The University of Tokyo
• Principal Investigator: Hirabayashi Shinichiro 東京大学, 大学院新領域創成科学研究科, 准教授 (90463877)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 浮体式プラットフォーム / 渦励起運動 / 複数カラム / 低アスペクト比 / 機械学習 / 共振

Outline of Final Research Achievements

The trend of hydrodynamic forces caused by vortex interference between columns of a semi-submersible floater in a flow was clarified by constructing a hydrodynamic force database based on model experiments, and the possibility and limitation of estimation by mathematical models were shown. It was shown that each fluid force of four circular cylinders from the database of two cylinders was accurately estimated by machine learning, and our initial goal of estimating fluid forces at arbitrary numbers and locations was achieved under partial condition. As a new finding concerning vortex-induced motion, it was shown for the first time that the vortex-induced motion in the vertical direction such as heave, pitch, and roll can happen for the floater with horizontally extending cylindrical member in the submerged part, which have never been focused on so far.

Free Research Field

海洋工学

Academic Significance and Societal Importance of the Research Achievements

浮体式洋上風車の浮体部として今後活用が見込まれるセミサブ型は没水部が複数の細長い部材で構成され、流れの中で各部材から放出される渦、あるいはそれらの干渉により複雑な浮体運動を生じる。本研究の成果により、この渦干渉の影響は数理モデルや機械学習を用いて簡易的に予測できることが示され、今後データベースを充実させることにより、将来的には浮体設計に生かせるレベルの実用的なモデル開発に繋がる知見を得た。本研究で新たな知見として得られた縦方向の渦励起運動についても、同様に簡易モデルで扱うことができると考えられる。