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

• 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
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06651079/
• 关键词: Boundary-element method; Iso-parametric element; Green function; Seakeeping performance; Nonlinear effects; Slender-ship theory; 高次境界要素法; スプライン要素; 前進速度影響; 自由表面影響

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.

本项目的主要目的是将高阶边界元法（HOBEM）应用于未解决或未解决的耐波性问题。特别是着重研究了船舶在波浪中的振动和平移的水动力问题，并采用二次或三次等参单元的HOBEM法编制了计算程序，该程序具有计算精度高、计算时间短的特点。主要研究结果如下：1）对满足自由面和辐射条件的绿色函数在计算时间上进行了改进; 2）基于该绿色函数的高阶边界元法，推导了一个新的积分方程，合理地考虑了船舶定常平移引起的定常扰动对非定常自由面条件的影响; 3）发展了一种新的细长船理论，该理论能合理地考虑船舶的航速和三维效应。采用二次等参元进行了数值计算，得到了特解。4）采用三维拉格朗日元对大型浮式结构物的浮托力进行了数值计算，该单元是一种高阶单元。采用二次单元法编制了二维浮体大幅振动时域全非线性仿真程序。本文还利用三次B样条函数编制了计算浅吃水巨型浮体水动力的计算机程序。结果表明，即使在波长很短的区域，通过检查能量守恒原理的精度也是极好的。

项目成果

柏木 正,向上 登志夫: "大規模浮体における流体力学的相互干渉の一計算法" 日本造船学会第13回海洋工学シンポジウム. 247-254 (1995)

Tadashi Kashiwagi、Toshio Kozo：“大型浮体中水动力相互干扰的计算方法”，日本造船学会第13届海洋工程研讨会247-254（1995）。

Kashiwagi, M.: "Time-Domain Full-Nonlinear Wave Radiation by a 2-D Floating Body" Proc.of 4th Symp.on Nonlinear and Free-Surface Flows. 17-20 (1995)

Kashiwagi, M.：“二维浮体的时域全非线性波辐射”Proc.of 4th Symp.on 非线性和自由表面流。

柏木,正、岩下,英嗣、高木,健、安川,宏紀: "三次元理論による計算法" 日本造船学会運動性能研究委員会第11回シンポジウム. 219-292 (1994)

Kashiwagi，Masaru，Iwashita，Hidetsugu，Takagi，Ken，Yasukawa，Hiroki：“基于三维理论的计算方法”日本造船学会运动性能研究委员会第11次研讨会219-292（1994）。

Kashiwagi Masashi: "Prediction of Surge and Its Effects on Added Resistance by Means of the Enhanced Unified Theory" 西部造船会会報. 89. 77-89 (1995)

Masashi Kashiwagi：“通过增强统一理论预测浪涌及其对附加阻力的影响”西方造船师协会公报 89. 77-89 (1995)。

Kashiwagi Masashi: "A New Slender-Ship Theory with Arbitrary Forward Speed and Oscillation Frequency" Proc. of 10th Int. Workshop on Water Waves and Floating Bodies. 109-114 (1995)

柏木正史：“具有任意前进速度和振荡频率的新细长船理论”Proc。