The occurrence probability prediction model of 2D and 3D freak waves generated by wave superposition

Abstract

The wave superposition is a common method to generate freak waves by assigning energy of wave spectrum to a focusing wave train and a random wave train. Traditionally, the freak wave generation by wave superposition requires repeatedly try for many times before obtaining satisfactory results. In this process, freak wave may not occur when wave component number or energy portion of focusing wave train is small and freak wave may break up when that is too large. It may also contribute to the discrepancy of significant wave height between target value and generated result when energy portion of focusing wave train is large. To improve simulation efficiency, the paper proposes a model to quantitatively predict the occurrence probability of freak waves in superposition cases of two and three wave trains. The error of significant wave height could be artificially controlled. The occurrence probability prediction model of freak wave is also extended to three-dimensional wave fields. The accuracy is well validated by statistical data. According to prediction results, two-dimensional and three-dimensional freak waves are successfully generated.