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Green-Naghdi (G-N) theory is a fully nonlinear theory for water waves. Some researchers call it a fully nonlinear Boussinesq model. Different degrees of complexity of G-N theory are distinguished by “levels” where the higher the level, the more complicated and presumably more accurate the theory is. In the research presented here a comparison was made between two different levels of G-N theory, specifically level II and level III G-N restricted theories. A linear analytical solution for level III G-N restricted theory was given. Waves on a planar beach and shoaling waves were both simulated with these two G-N theories. It was shown for the first time that level III G-N restricted theory can also be used to predict fluid velocity in shallow water. A level III G-N restricted theory is recommended instead of a level II G-N restricted theory when simulating fully nonlinear shallow water waves. 相似文献
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非结构化网格浸入边界法的流固耦合数值模拟(英文) 总被引:1,自引:0,他引:1
This paper presents an improved unstructured grid immersed boundary method. The advantages of both immersed boundary method
and body fitted grids which are generated by unstructured grid technology are used to enhance the computation efficiency of
fluid structure interaction in complex domain. The Navier-Stokes equation was discretized spacially with collocated finite
volume method and Euler implicit method in time domain. The rigid body motion was simulated by immersed boundary method in
which the fluid and rigid body interface interaction was dealt with VOS (volume of solid) method. A new VOS calculation method
based on graph was presented in which both immersed boundary points and cross points were collected in arbitrary order to
form a graph. The method is verified with flow past oscillating cylinder. 相似文献
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丹东港大东港区是高桩栈桥式码头,单位荷载有限,在散货装船时不能提前备货。船舶靠港后,一边上货一边采用门机抓斗装船,作业过程中,码头作业现场门机、自卸汽车、装载机形成交叉作业,既不利于安全生产和环保要求,又影响作业效率,装船成本高,同时对其他泊位集疏港车辆的通过也有妨碍。 相似文献
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针对堤防混凝土衬砌在外部荷载(水压力、浪压力以及其他荷载)发生破坏且其破坏位置主要发生在衬砌底部1/3处的问题,进行了对比分析研究,提出一种"自适应"的混凝土衬砌方式。采用有限元软件ADINA模拟在衬砌受力最大部位设置填充缝及填充柔性材料等方式削减应力,从而达到衬砌自身适应外部荷载变形的作用。结果表明:"自适应"衬砌方式不仅可以有效减小堤防的应力、应变,而且是一种实用简单可行的方法。 相似文献
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陶瓷/液舱复合结构抗侵彻机理试验研究 总被引:2,自引:0,他引:2
为探讨EFP战斗部的防护方法,文章根据陶瓷材料和液舱结构的抗侵彻机理,提出在舰船防护液舱前增设抗弹陶瓷材料层抵御大质量弹丸的侵彻,设计了1/10缩尺的防护液舱结构模型,开展了3类陶瓷/液舱复合结构抗侵彻试验研究,分析了弹体、液舱前、后面板的破坏模式和侵彻过程以及复合结构的抗侵彻效能.结果表明:弹体主要发生墩粗-侵蚀破坏;液舱结构前面板的破坏分为剪切冲塞(花瓣开裂)、碟形变形、薄膜鼓胀和失稳凹陷四个阶段;后面板的破坏随板的厚度而变化:后板较厚时发生剪切冲塞,较薄时发生花瓣开裂;初始压力峰值远远大于空化载荷峰值,但空化载荷对结构的破坏起着主要作用. 相似文献
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采用求解RANS方程和基于VOF方法的非定常粘性数值方法并结合湍流模型对球体在两层流体中水下运动时的尾迹特征进行了针对性的研究,成功模拟出球体在水下运动产生的表面波和内波,与理论分析及其文献研究计算结果进行对照,取得了较为一致的结果,为进一步使用粘性CFD方法系统研究分层流体中潜体运动尾迹的生成机理、传播特性等问题打下了坚实的基础. 相似文献
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均匀流中潜艇水下运动表面尾迹的数值模拟 总被引:11,自引:0,他引:11
本文通过基于RANS方程和VOF方法的非定常粘性数值方法对潜艇在均匀流中水下运动的表面尾迹特征进行了探索性研究,较好地解决了用粘性流方法来模拟远场波浪中的数值耗散问题,数值计算得到的潜艇运动尾迹特征与诸多文献和理论分析结果基本一致.本文均匀流中的数值模拟将成为潜艇在分层流运动数值模拟的基础. 相似文献
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船与FRP浮箱非线性动力学碰撞过程的数值仿真 总被引:1,自引:0,他引:1
介绍了自定位防船撞FRP浮箱的结构特点;基于ANSYS/LS-DYNA软件平台,对一艘2000DWT散货船与防撞浮箱正撞和8°斜撞的非线性动力学过程进行了数值仿真研究;分析了能量耗散过程、碰撞力衰减时程以及碰撞区的结构变形与损伤失效过程;为该装置的工程设计与工程实验提供了理论依据。 相似文献
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基于粘流理论、流固耦合理论和自由液面追踪技术——VOF(Volume of Fluid)法,以不可压缩流体的连续方程和N-S方程及结构动力学方程为基本控制方程,利用商用软件ANSYS Workbench的二次开发功能,建立了粘性数值波浪水池,数值模拟了完全非线性波的生成,计算分析了二维浮式结构物遭遇波浪的完全非线性现象,得到了甲板上浪水位高度和结构物的纵摇、垂荡、横摇等运动响应。结果表明:文中的方法可以用于波浪与浮式结构物相互作用的完全非线性数值模拟. 相似文献
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为探究钢与玻璃钢的组合结构形式对舰船舱壁复合装甲结构抗穿甲性能的影响,采用均质钢板前置和后置玻璃钢来分别模拟舰船舱壁外设及内设复合装甲结构,结合高速弹道冲击实验,分析、比较2种结构形式组合靶板的穿甲破坏模式和抗弹吸能能力。在此基础上,利用有限元分析软件ANSYS/LS-DYNA开展高速立方体弹丸侵彻组合靶板的数值模拟计算,分析组合靶板的侵彻过程,并与实验结果进行比较。结果表明,数值计算结果与实验结果较为吻合;2种组合靶板中复合装甲板的破坏模式均主要为钢板的剪切冲塞破坏和玻璃钢的纤维剪切断裂,后置组合靶板中玻璃钢背层伴随有纤维的拉伸破坏;前置组合靶板的抗弹吸能能力要稍大于后置组合靶板。 相似文献
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大压差工况下,船舶内部液舱自流注水时管路振动噪声问题突出。采用有限体积法离散大涡模拟的流体控制方程,计算分析典型工况下注水系统管内流场。考虑管内液体对管道结构振动的影响,计算注水管路的“湿模态”。以管路壁面流体压力脉动作为激励源,基于有限元法对流固耦合作用下管道结构的振动和流激振动辐射噪声进行数值模拟。对阀门上下游不同监测点的流激振动噪声频谱进行分析,探究管路流激振动噪声产生、传播和衰减规律。分析结果表明:注水系统管道结构流激振动噪声沿管道传播基本无衰减;流激振动噪声频带较宽,主频率为80 Hz;管道结构的流激振动噪声整体幅值较大,需要采取增加弹性管卡等措施进行治理。 相似文献
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The virtual erection simulation system was explained for a steel structure including ship and ocean plant blocks.The simulation system predicted the erection state to optimize any gap or overlap of blocks based on 3-D measurement data.The blocks were modified(cut) on the basis of the simulation result on the ground before erecting them by crane.The re-cutting process was not required and the blocks were erected into a mother ship speedily.Therefore,the erection time is reduced,increasing the dock turnover. 相似文献
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ZONG Zhi DONG Guo-hai 《船舶与海洋工程学报》2007,6(2):1-5
Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analysis of their impact would be impossible without numerical simulations. In this paper, a pressure-split two-stage numerical algorithm is proposed based on Volume Of Fluid (VOF) methodology. The algorithm is characterized by introduction of two pressures at each half and full cycle time step, and thus it is a second-order accurate algorithm in time. A simplified second-order Godunov-type solver is used for the continuity equations. The method is applied to simulation of breaking waves in a 2-D water tank, and a qualitative comparison with experimental photo observations is made. Quite consistent results are observed between simulations and experiments. Commercially available software and Boundary Integral Method (BIM) have also been used to simulate the same problem. The results from present code and BIM are in good agreement with respect to breaking location and timing, while the results obtained from the commercial software which is only first-order accurate in time has clearly showed a temporal and spatial lag, verifying the need to use a higher order numerical scheme. 相似文献
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针对高桩墩台式码头结构特点,对受事故影响的某码头结构进行检测,并通过数值模拟分析事故对码头结构的影响,将现场检测结果同数值模拟分析相比较,验证了事故发生后高桩墩台式结构影响范围及事故发生后码头结构的响应程度. 相似文献