Effects of strong wind on overtopping characteristics of tidal bores at coastal seawall

A tidal bore is known for its abrupt change in water flow with a complex and violent leading front. The powerful tidal bore can quickly move up the sloped beach and overtop the seawall, leading to significant damages along the coast. In the past, many coastal seawalls were constructed to shield the coastal regions from the destructive power of tidal bores. The typhoon-induced shear force and pressure imbalance can significantly affect the tidal bore height and its propagation speed. Therefore, it is important to evaluate how strong winds impact the hydrodynamic transformation and overtopping of tidal bore at the seawalls. However, there are few research on this topic. To address the limitations of previous research, this study applies a high-resolution two-phase flow solver to numerically examine how strong winds impacts the overtopping characteristics of tidal bore at coastal seawalls. The effects of main factors, including wind speed, tidal bore height, water depth, and beach slope, are thoroughly examined. Research findings indicate that the presence of wind can cause notable changes in the hydrodynamic evolution and overtopping characteristics of both undular tidal bore and weak breaking tidal bores, whereas its impact on the overtopping characteristics of breaking tidal bore is relatively limited. Simultaneously, the presence of wind can significantly increase the intensities of the undular tidal bore and weak breaking tidal bore at the seawall. The high nonlinear behavior of the breaking tidal bore at the seawall is demonstrated by its impactful intensity when influenced by wind. It is hoped that the present study will enhance knowledge on the hydrodynamic overtopping characteristics of tidal bores in harsh weather conditions. •Hydrodynamic overtopping processes of different types of tidal bores at the seawall under the wind have been numerically investigated by applying a high-resolution two-phase flow solver.•Influences of major factors, such as wind speed, tidal bore height, initial water depth, and beach slope are investigated in detail.•Research results reveal that the wind can noticeably reshape the hydrodynamic evolution and overtopping characteristics of the undular tidal bore and weak breaking tidal bore, except the breaking tidal bore.