COMPARATIVE STUDY ON NUMERICAL SIMULATION OF FLOW AROUND A VERY LARGE FLOATING STRUCTURE

超大型浮体绕流数值模拟对比研究

• 批准号: 07305066
• 负责人: KYOZUKA Yusaku
• 金额: $ 1.54万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07305066/
• 关键词: Very Large Floating Structure; Tidal Calculation; Diffusion Calculation; Environmental Assessment; 海洋拡散計算

Needs for ocean space utilization will be increased more and more in future. Large part of coastal area shallower than 20m has been reclaimed to utilize for the industrial and residential purpose and the utilization of deeper area is necessary in future. A feasiblity research project on large-scale floating structures for ocean space utilization is now being conducted in Japan. Floating structures are superior to a reclaimed island in some aspects such as having less impact on the ocean environment. Because the scale is huge compared with those which now exist, however, environmental assessment of such a structure in a bay is necessary before construction. This cooperative study deals with the numerical methods used for the simulation of the flow and the diffusion of a bay with a large-scale floating structure. The validation and the accuracy of the methods are discussed by the comparative calculations. The studies covered during two years are summarized as follows :(1) Simulations of … More the flow and diffusion of a rectangular bay with a large-scale floating structure is compared by the finite difference methods (ADI method and Leap-Frog method) and the finite element method in two-dimensional plane.(2) A multi-level method is applied for the same problem and the result is compared with two-dimensional calculations.(3) Visualization of the flow around a model of the floating structure in a tidal tank is compared with the calculations. As an example of more practical case, two-and three-dimensional simulations are conducted for a large-scale floating structure in Tokyo bay.(4) Tidal currents and the residual currents by two-dimensional methods and a multi-level model are compared.(5) The diffusion patterns of COD (Chemical Oxygen Demand) from rivers inside the bay are compared by the methods.Results obtained from these studies are summarized as follows :(1) Two-dimensional results are equivalent to the vertical integration of the multi-level solution.(2) ADI-method is superior to Leap-Frog method in the numerical stability, it can take longer time-steps. Programming of Leap-Frog method, however, is much easier than ADI-method and the numerical accuracy is almost same between them.(3) A large-scale floating structure causes less effects on the flow and the diffusion in the bay than a reclaimed island.(4) A multi-level model is more effective to obtain the steady solution of COD in a short computational time than two-dimensional methods. Less

未来对海洋空间利用的需求将越来越大。大部分浅于20米的海岸地区已被填海用于工业和住宅目的，未来有必要利用更深的地区。日本目前正在进行一项关于利用海洋空间的大型浮式结构物的可行性研究项目。浮式结构物在某些方面上级填海造岛，例如对海洋环境的影响较小。然而，由于其规模与现有的结构相比是巨大的，因此在施工前需要对海湾中的这种结构进行环境评估。本合作研究系探讨大型浮式结构物在海湾内之流动与扩散之数值模拟方法。通过对比计算，讨论了方法的有效性和准确性。在这两年中所涵盖的研究概述如下：（1）模拟 ...更多信息 本文采用有限差分法（ADI法和蛙跳法）和二维有限元法对带有大型浮式结构的矩形海湾的流动和扩散进行了比较。(2)一个多层次的方法适用于同一问题，并与二维计算结果进行了比较。(3)在潮汐槽中的浮式结构的模型周围的流动的可视化与计算进行了比较。作为一个更实际的情况下，二维和三维模拟东京湾的大型浮式结构进行。(4)比较了二维潮流计算和多层模型计算的余流和潮流。(5)通过对湾内河流COD（Chemical Oxygen Demand）扩散模式的比较，得到以下结论：（1）二维结果与多层解的垂向积分是等价的; (2)ADI方法在数值稳定性方面比Leap-Frog方法有上级的优点，但可以采用更长的时间步长。而蛙跳法的程序编制比ADI法简单得多，数值精度与ADI法相当。(3)大型浮式建筑物对海湾内水流和扩散的影响小于填海造岛。(4)多层模型比二维模型能更有效地在较短的计算时间内获得COD的稳定解。少

项目成果

Y.Kyozuka: "Numerical Simulation of Tidal Flow and Density Field around a Mega-Float in a Bay" Proc.of Techno-Ocean'96. II. 633-638 (1996)

Y.Kyozuka：“海湾巨型浮体周围潮汐流和密度场的数值模拟”Proc.of Techno-Ocean96。

M.Fujino: "On the Sea-Covering Effect of a Huge Floating Structure on the Surrounding water" Journal of the Society of Naval Architects of Japan. Vol.180. 393-402 (1996)

M.Fujino：“论大型漂浮结构对周围水域的海洋覆盖效应”日本造船学会杂志。

Y.Kyozuka: "Numerical Simulation of Tidal Flow and Density Field around a Mega-Float in a Bay" Techno-Ocean′96 Int.Symp.Proc.II. 633-638 (1996)

Y.Kyozuka：“海湾巨型浮体周围潮汐流和密度场的数值模拟”Techno-Ocean96 Int.Symp.Proc.II 633-638 (1996)

S.Hanada: "Flow Field Around a Body Penetrating a Density Interface" Journal of the Kansai Society of Naval Architects, Japan. No.225. 239-248 (1996)

S.Hanada：“穿透密度界面的物体周围的流场”，日本关西造船学会杂志。

C.Hu: "Tidal simulation of a Bay with a Very Large Floating Structures, Using a Multi-Level Model" Proc.of 1996 OMAE,ASME. Vol.1-A. 23-30 (1996)

C.Hu：“使用多级模型对具有非常大的浮动结构的海湾进行潮汐模拟”Proc.of 1996 OMAE，ASME。