畸形波作用下海洋平台小尺度杆件波浪荷载分析

A time-domain analysis of wave force on small-scale cylinders of platform under freak waves

为准确计算复合结构中小尺度杆件上的波浪荷载,不仅要考虑入射波浪作用,还应该考虑大尺度结构物对波浪的绕射以及辐射影响.以畸形波对固定圆柱作用产生的绕射场为例,用Morison公式计算绕射场作用下细小杆件的波浪荷载.用高阶边界元法建立波浪对结构物作用的时域计算程序,利用积分方程求域内水质点由绕射势产生的速度和加速度.结果显示,在一定波浪条件下,杆件上的总波浪力为入射波浪力的1.2倍.因此,在工程中应充分考虑复合结构中由于大尺度结构物存在产生的绕射和辐射作用对细小杆件的波浪力.

To get the accurate wave loads on the small-scale cylinders in the composite structure,the incident wave and the diffraction and radiation waves must be considered.The freak wave diffraction from a fixed large-scale cylinder was taken as an example,and the wave loads on small-diameter cylinders in the diffraction wave field were calculated by using Morison formula.A time-domain numerical model on wave diffraction from large-scale structures was developed with a higher-order boundary element method,and then the velocity and acceleration of any water particle in the fluid domain can be produced from the solved diffraction potential.Results show that the total wave force is 1.2 times as large as incident wave force under some wave conditions.Therefore,the wave force on the stake produced by the diffraction waves due to existence of the upper structures should be considered in engineering.