Effect of wave and wind speed fluctuations on drag coefficient

2022 Fiscal Year Final Research Report

• Project/Area Number: 18H01284
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Kindai University
• Principal Investigator: Suzuki Naoya 近畿大学, 理工学部, 教授 (40422985)
• Co-Investigator(Kenkyū-buntansha): 高垣 直尚 兵庫県立大学, 工学研究科, 准教授 (00554221) ; 早稲田 卓爾 東京大学, 大学院新領域創成科学研究科, 教授 (30376488)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 風の海面摩擦係数 / 風速・風向変動 / 表層流 / うねり / 海面状態

Outline of Final Research Achievements

The effect of the fluctuation of waves and wind speed on the variation factor of the drag coefficient for the wind speeds was investigated in a laboratory and field. The knowledge about the variation of the drag coefficient on the presence of component wave and surface current with following wind wave and was obtained by laboratory measurements. The knowledge about the variation of the drag coefficient on the fluctuation of the time-series of mean wind speed and significant wave height and the fluctuation of the instantaneous wind speed were obtained by field measurements. In addition, new knowledge was obtained that the fluctuation of wind direction is also a factor in the variation factor of the drag coefficient. And The method using the IMU sensor for more accurate observation was proposed using the small wind stress and wave buoy.

Free Research Field

海洋物理

Academic Significance and Societal Importance of the Research Achievements

地球環境変化やその基礎となる気候システムの変動・変化の最も基本的な要素の１つである大気・海洋間運動量フラックスを求めるための重要なパラメータである風の海面摩擦係数が風速に対して大きく変動し、その変動要因の知見が十分でないため、精度の良い風の海面摩擦係数モデルは確立されていない。本研究は、風の海面摩擦係数の変動要因として波浪の影響のみでなく海面上を吹く風速の変動に着目し、波浪の影響のみならず風速・風向変動によっても風の海面摩擦係数の変動要因となる知見が得られ、さらにブイで高精度観測を行うための新たな手法を提案したことに学術的および社会的な意義がある。