Wave Impact On The Three-dimensional Open Structure

With the development of the ocean exploitation on Tweenty-one centrury, more and more open structures, such as offshore oil platforms, detached wharfs and open style wharfs etc. are built up in deep water. However, because of under-design altitude of the panel, the settlement of the seabed etc., while encountering the abominable sea-conditions, the wave-impact force caused by the wave slamming when the water contacts the subface of the structure threaten the stability and safety of the superstructures. Thus, the forecast of wave slamming loads in the design of coastal and offshore engineering is more and more valued and has become an important subject. It is significant to research the characteristics in the process of the wave impact deeply.This paper presents the experimental investigation of the slamming on the three-dimensional open structure in the splash zone, and also the contrastive analysis by the numerical simulation results.First of all, the experimental investigation of the slamming on the three-dimensional open structure in the splash zone is developed. The statistical distribution characteristics of the perpendicular wave impact pressures are compared with that of the oblique wave on the underside of the open structure. The relation between wave impact forces and the parameters such as the relative wave height, the relative structure width and the relative clearance of the structure is also discussed. The effect of the wave direction ft on the wave impact forces on the underside of the structure is determined. The spectral analysis of unidirectional irregular wave slamming is presented. The distribution characteristics of the zeroth order moment of the perpendicular and oblique wave impact pressure spectrum along the subface of the structure are given. And the effect of different incident wave parameters such as the relative wave height, the relative structure width and the relative clearance on the nondimensional zeroth order moment of the impact force spectrum are discussed. The experiential expressions of the dimensionless zeroth order moment of the impact force spectrum for different wave incident angles are summarized. And also the empirical expression of the impact forces and zeroth order moment of the impact force spectrum are given.Then, the three-dimensional numerical wave basin based upon the VOF method is established. VOF is used for tracing the free surface, the governing equations are continuity equation and N-S equations, based on the linear wave theory, wave-maker is set, and the numerical sponge layer and SRC achieve the damping elimination to the incident wave, the radical sign style of the attenuation quotient is chosen. In connection with the wave slamming problem, the three-dimensional wave impact boundary conditions are introduced. The numerical computation results of wave impact on the three-dimensional foursquare open structure in the splash zone for different parametric cases are verified by the experimental results. Meanwhile, the characteristics of the wave impact pressures and wave impact forces on the underside of the rectangular structure with different length-breadth ratio are given. New calculation method is provided for the study of three-dimensional wave slamming problem.