Experimental Study on the Wavelengths of Two-Dimensional and Three-Dimensional Freak Waves

作     者：CUI Cheng PAN Wen-bo CUI Cheng;PAN Wen-bo

作者机构：National Engineering Research Center for Port Hydraulic Construction TechnologyM.O.T.Tianjin Research Institute of Water Transport EngineeringTianjin 300456China 

出 版 物：《China Ocean Engineering》 (中国海洋工程（英文版）)

年 卷 期：2023年第37卷第1期

页      面：154-164页

核心收录：

学科分类：081505[工学-港口、海岸及近海工程] 08[工学] 0815[工学-水利工程] 0824[工学-船舶与海洋工程] 0814[工学-土木工程] 082401[工学-船舶与海洋结构物设计制造] 

基　　金：financially supported by the National Natural Science Foundation of China (Grant Nos.51509120 and 52171260) the Basic Funding of the Central Public Research Institutes (Grant No.TKS20200317) 

主　　题：freak wave rogue wave wavelength three-dimension directional spread multidirectional wave 

摘      要：Freak waves are commonly characterized by strong-nonlinearity, and the wave steepness, which is calculated from the wavelength, is a measure of the degree of the wave nonlinearity. Moreover, the wavelength can describe the locally spatial characteristics of freak waves. Generally, the wavelengths of freak waves are estimated from the dispersion relations of Stokes waves. This paper concerns whether this approach enables a consistent estimate of the wavelength of freak waves. The two-(unidirectional, long-crested) and three-dimensional(multidirectional, shortcrested) freak waves are simulated experimentally through the dispersive and directional focusing of component waves, and the wavelengths obtained from the surface elevations measured by the wave gauge array are compared with the results from the linear, 3rd-order and 5th-order Stokes wave theories. The comparison results suggest that the 3rd-order theory estimates the wavelengths of freak waves with higher accuracy than the linear and 5th-order theories. Furthermore, the results allow insights into the dominant factors. It is particularly noteworthy that the accuracy is likely to depend on the wave period, and that the wavelengths of longer period freak waves are overestimated but the wavelengths are underestimated for shorter period ones. In order to decrease the deviation, a modified formulation is presented to predict the wavelengths of two-and three-dimensional freak waves more accurately than the 3rd-order dispersion relation, by regression analysis. The normalized differences between the predicted and experimental results are over 50% smaller for the modified model suggested in this study compared with the 3rd-order dispersion relation.