Numerical study of waves breaking on a vertical pile with different cross-sections

Abstract

A three-dimensional numerical model is established to simulate the interaction between breaking waves and a vertical pile. The primary aim of this study is to explore the influence of pile cross-section shape on inline wave forces under different wave breaking stages. Besides the common circular, squircle, and square cross-sections, a novel pile proposed by Yang et al. (2020), consisting of a front diamond surface and a circular back, is also considered. A comparison of breaking wave force characteristics is performed for these four piles in various wave steepnesses. The results indicate that changes in the cross-section shape result in alterations to the inline force magnitude, whereas the transitions of the wave breaking stage not only quantitatively modify the inline force magnitude but also qualitatively alter the force curve shape. Special attention is then paid to a detailed analysis of the flow evolution and force distribution to gain insights into the generation of the peak force and the secondary load cycle (SLC). Furthermore, the numerical results are analyzed in the frequency domain, revealing that higher harmonics beyond the eighth order are not associated with the SLC, but are intimately related to the peak breaking wave force.