Wave impact force and dynamic pressure on a monopile under different scenarios of focused breaking waves

Cylindrical slender members are typical compositions of many offshore and harbor structures. Extreme wave impact loading on such monopile structure is a very important problem as the slamming force acts for a very short period of time and the magnitude of the load is high. This study aims to estimate the breaking impact dynamic force on a monopile based on the numerical simulational results to analyze the loading characteristics in finite water depth. The simulation of the interaction between the focused breaking waves and monopile is carried out in a numerical wave tank established based on the two-phase flow model in REEF3D, the open-source computational fluid dynamics program. The fluid field is governed by the Reynolds-averaged Navier-Stokes equation. Two equation k-w turbulence models are adopted to model the turbulence structures during the complicated chaotic interaction process between the focused breaking wave and a single vertical cylinder. Four different locations of typical breaking scenarios are chosen to investigate the breaking loading variation during the breaking process. The situation when the wave breaks after the structure is selected in a wave-breaking process to evaluate the quasi-static force. Based on this method, the dynamic loading due to wave breaking can be evaluated. The harmonic structure of the dynamic force is analyzed using the FFT method. The slamming force on the cylinder is different as wave-breaking intensities change during the breaking process. The dynamic pressure and wave run-up on the cylinder are also investigated under four typical breaking situation.