Study on Numerical Calculation Method for the Seakeeping of Ships by Means of Higher-Order Boundary-Element Method

高阶边界元法船舶耐波性数值计算方法研究

基本信息

批准号：
06651079
负责人：
KASHIWAGI Masashi
金额：
$ 1.34万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

A main purpose of the present project was to apply the higher-order boundary-element method (HOBEM) to unsettled or unsolved seakeeping problems. In particular, emphasis is placed on the hydrodynamic problem of an oscillating and translating ship in waves, in which the HOBEM using quadratic or cubic iso-parametric elements was applied todevelop a computer program with high accuracy and less computation time. Obtained results are summarized as follows :1)Improvement was made on the Green function satisfying the free-surface and radiation conditions, in terms of the computation time.2)A new integral equation based on the HOBEM using the above Green function was derived, in which the effect of steady disturbance due to ship's steady translation on the unsteady free surface condition was rationally taken into account.3)Development was made of a new slender-ship theory which can account for the forward-speed and 3-D effects in a rational way. Numerical computations based on this new theory were also performed, in which quadratic iso-parametric elements were adopted to obtain numerically the particular solution.4)The 3-D Lagrange element, which is one of the higher-order elements, was used to compute the drift force from the pressure integration acting on multiple bodies supporting a very large floating structute. It was shown that the results were very accurate.5)A time-domain full-nonlinear simulation program for the large-amplitude oscillation of a 2-D floating body was developed using quadratic elements. The results were very primising.Also developed was a computer program for predicting the hydrodynamic forces on a shallow-draft huge floating structure, by use of the cubic B-spline function. It was shown that the accuracy by checking the energy-conservation principle was excellent even for the region of very short wavelengths.

本项目的一个主要目的是将高阶边界元素方法（HEBEM）应用于未解决或未解决的海务问题。特别是，重点放在波浪中振荡和翻译船上的流体动力问题上，其中使用了使用二次或立方体或立方体参数元素的霍比姆（Hebem），以高精度和较少的计算时间进行了计算机程序。总结如下：1）对满足自由表面和辐射条件的绿色功能进行了改进。 3-D效果以合理的方式。还进行了基于此新理论的数值计算，其中采用了二次等二个元素以数值以获得特定的解决方案。4）3-D Lagrange元素是高阶元素之一，用于计算从支持多个浮动结构的多个物体上的压力积分的漂移力。结果表明，结果非常准确。5）使用二次元素开发了一个时间域的全非线性仿真程序，用于二维浮动体的大振幅振荡。结果也很原始。也是开发的是一种计算机程序，用于通过使用立方B-Spline功能来预测浅水放射线巨大浮动结构上的流体动力。结果表明，即使对于非常短的波长区域，通过检查能量保存原理的精度也是如此。