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Theory of non-linear wave forces acting on an offshore structure in a shallow water and comparison with experiments

浅水中海上结构的非线性波浪力理论及与实验的比较

基本信息

批准号：
12450406
负责人：
KINOSHITA Takeshi
金额：
$ 6.72万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450406/
关键词：
non-linear wave force ringing moored floating body secular term wave drift damping wave drift added mass wave drift force 非線形流体力係留

项目摘要

Non-linear wave forces act essential role on non-linear responses of an offshore structure such as a tension leg platform. It has not been established yet to theoretically estimate them in case of higher than 3^<rd> order. It is mainly because of secular terms which appear in a free-surface condition in case of perturbation approach. Molin shown that numerical filtering is useful to avoid them, but his method cannot apply to the problem in case of shallow water. In this research we have formulated 3^<rd> order wave force acting on a circular cylinder in shallow water, and studied general mathematical behavior of the secular terms. Another important and interesting subject of a secular terms is a wave drift added mass, which is very important to estimate slow drift oscillation of a moored floating body in irregular waves, as well as a wave drift damping. We have formulated the problem by a perturbation method with two small parameters which are wave slope and motion frequency. Secular terms appear in the higher order problems, similarly to the 3^<rd> order wave force problem. We have firstly obtained radiation conditions to set unique solutions. The obtained solutions were compared with the measured date obtained by newly developed experimental set-up.

非线性波浪力对海上结构（例如张力腿平台）的非线性响应起着至关重要的作用。在高于 3^<rd> 阶的情况下，尚未建立理论上的估计它们。这主要是因为在扰动方法的情况下出现在自由表面条件下的长期项。莫林表明，数值过滤对于避免这些问题很有用，但他的方法不适用于浅水情况下的问题。在这项研究中，我们制定了作用在浅水中圆柱体上的 3^<rd> 阶波浪力，并研究了长期项的一般数学行为。世俗术语的另一个重要且有趣的主题是波漂移附加质量，这对于估计不规则波浪中系泊浮体的慢漂移振荡以及波漂移阻尼非常重要。我们通过扰动方法用两个小参数（波斜率和运动频率）来表述该问题。长期项出现在高阶问题中，类似于 3^<rd> 阶波浪力问题。我们首先获得了辐射条件来制定独特的解决方案。将获得的解决方案与新开发的实验装置获得的测量数据进行比较。