仿鱼尾潜器推进系统的水动力分析   总被引：21，自引：3，他引：21  

苏玉民  黄胜等 《海洋工程》2002,20(2):54-59

以开发适用于小型潜器的仿生操纵与推进系统为研究背景 ,对金枪鱼的月牙形尾鳍进行水动力分析。文中将金枪鱼的尾鳍处理为在做横移和摇摆的耦合运动的同时 ,以某一匀速向前运动的月牙形刚性尾翼。计算中应用了双曲面元和压力库塔条件 ,利用面元法计算分析该三维尾翼的非定常水动力性能。探讨了前进速度、横荡和摇首的幅度、频率及其相位差对推进性能的影响  相似文献   

Effect of shallow and narrow water on added mass of cylinders with various cross-sectional shapes     

Z.X. Zhou  Edmond Y.M. Lo  S.K. Tan 《Ocean Engineering》2005,32(10):1199-1215

The sway, heave and roll added masses of three uniform cylinders with semi-circular, rectangular and triangular cross-sectional shapes in shallow and narrow water are numerically analysed. The method is based on simulation of the potential flow induced by the cylinder's mode of motion. The effects of shallow and narrow water on added mass are analysed and presented. It is concluded that the shallow and narrow water effects on added mass depend on the different cross-section shapes of the cylinders. In particular, the water depth effect on sway added mass is stronger than that on heave added mass while the narrow water effect on sway is weaker than that on heave. The shallow water effect on added mass tends to weaken the narrow water effect. Lastly the effect of shallow and narrow water on added mass on a rectangular cylinder is the strongest while that on a triangular cylinder is the weakest.  相似文献   

A new efficient 3D non-hydrostatic free-surface flow model for simulating water wave motions     

Doo Yong Choi  Chin H. Wu   《Ocean Engineering》2006,33(5-6):587-609

A new three-dimensional, non-hydrostatic free surface flow model is presented. For simulating water wave motions over uneven bottoms, the model employs an explicit project method on a Cartesian the staggered gird system to solve the complete three-dimensional Navier–Stokes equations. A bi-conjugated gradient method with a pre-conditioning procedure is used to solve the resulting matrix system. The model is capable of resolving non-hydrostatic pressure by incorporating the integral method of the top-layer pressure treatment, and predicting wave propagation and interaction over irregular bottom by including a partial bottom-cell treatment. Four examples of surface wave propagation are used to demonstrate the capability of the model. Using a small of vertical layers (e.g. 2–3 layers), it is shown that the model could effectively and accurately resolve wave shoaling, non-linearity, dispersion, fission, refraction, and diffraction phenomena.  相似文献   

一种新型混沌遗传优化算法的研究     

张海燕  潘成欣 《中国海洋大学学报(自然科学版)》2006,36(4):555-558

在对遗传算法交叉、变异后结果的处理方法进行改进并在将进化过程分段的基础上,提出1种新的混沌遗传算法。该算法利用混沌运动的遍历性择优产生初始群体,对每一轮遗传操作所得到的部分当前最优个体进行变尺度混沌搜索。仿真结果表明,该算法具有较高的优化效率,并能求得全局最优解。  相似文献   

大深度载人潜水器低速大漂角模糊滑模航向控制研究   总被引：1，自引：0，他引：1  

马岭  崔维成 《海洋工程》2006,24(3):74-78

通过模型试验测量大深度载人潜水器低速大漂角运动时所受到的非线性水动力。基于一种新的模糊滑模控制策略,为潜水器设计了鲁棒航向控制器。在不同的漂角子区间内分别设计局部镇定的滑模控制器,然后通过Takagi-Sugeno模糊推理系统将它们光滑连接,得到模糊滑模控制。仿真计算结果充分显示了该控制策略的有效性。  相似文献   

诊断台风异常路径的三层权重控制点方案     

谢玲娟  林丽珊 《海洋预报》1992,9(3):8-16

本方案采用850、700、500hPa三个层次的环境平均流场作控制点法。综合考虑这些层次上的引导气流在不同时、空域中的相对重要性。试验结果表明,其效果比单一取某层作引导为佳。且对用来预测台风的未来24小时路径是否异常具有一定的参考价值。  相似文献   

The Working Mechanism and An Analytic Method of the Deep Embedded Large Cylinder Structure     

孙克俐  周锡礽钱荣 《中国海洋工程》2004,18(2):221-228

The large cylinder is a new-type structure that has been applied to harbor and offshore engineering. An analytic method of the relationship between loads and the structure displacement is developed based on the failure mode of deep embedded large cylinder structures. It can be used to calculate directly the soil resistance and the ultirnate bearing capacity of the structure under usage. A new criterion of the large cylinder structure, which discriminates the deep embedded cylinder from the shallow embedded cylinder, is defined. Model tests prove that the proposed method is feasible for the analysis of deep embedded large cylinder structures.  相似文献   

Undular tidal bore dynamics in the Daly Estuary, Northern Australia   总被引：7，自引：0，他引：7  

Eric Wolanski  David Williams  Simon Spagnol  Hubert Chanson 《Estuarine, Coastal and Shelf Science》2004,60(4):629-636

Measurements in the macro-tidal Daly Estuary show that the presence of an undular tidal bore contributed negligibly to the dissipation of tidal energy. No recirculation bubble was observed between a trough and the following wave crest in the lee waves following the undular bore. This differs to stationary undular bores in laboratory experiments at larger Froude numbers where a recirculation bubble exists. Secondary motions and the turbulence generated by the undular bore had no measurable influence on the sediment transport. This situation contrasts with the intense sediment resuspension observed in breaking tidal bores. The tidally averaged sediment budget in the Daly Estuary was controlled by the asymmetry of tidal currents. The undular bore may widen the river by breaking along the banks that it undercuts, leading to bank slippage. A patch of river-wide macro-turbulence of 3-min duration occurred about 20 min after the passage of the bore during accelerating tidal currents.  相似文献   

Habitat characteristics and spatial arrangement affecting the diversity of fish and decapod assemblages of seagrass (Zostera marina) beds around the coast of Jersey (English Channel)     

Emma L. Jackson  Martin J. Attrill  Malcolm B. Jones 《Estuarine, Coastal and Shelf Science》2006,68(3-4):421

Recent research and management plans for seagrass habitats have called for landscape level approaches. The present study examines the spatial utilisation of subtidal seagrass beds by fish and decapods around the coast of Jersey (49°N 02° W). A hierarchical scale of landscape configuration and the plant characteristics of eight seagrass beds were measured and the contributions of these variables as predictors of the properties of the fish and decapod assemblages were evaluated using multiple linear regression models. The results indicated that total diversity had a negative relationship with transect heterogeneity and total species number had a weak negative association with increasing fragmentation. Both total diversity and total species number showed a positive relationship with depth. In fact, in all models of species number and densities, values were higher in deeper seagrass beds. Total decapod density increased with aggregation of seagrass patches within a landscape. In addition to landscape configuration, smaller-scale structural changes in both canopy height and epiphyte load appeared to influence densities of decapod crustaceans. At night, fewer patterns could be explained by the independent variables in the model.  相似文献   

泥石流平面形态的统计分析     

刘希林 《海洋地质与第四纪地质》1995,15(3):93-104

泥石流扇的平面形态可用规划的几何图形来模拟。在研究了中国西南地区小江流域和意大利东北部阿尔卑斯山区的５２个泥石流扇的基础上，本文提出了两种泥石流扇的平面形态：中国西南地区的“等腰三角形＋半圆形”泥石流扇和意大利东北部的“几何扇”。用统计分析建立了两组泥石流扇和泥石流流域之间的形态度量关系。通过两个研究区域的对比，两个流域参数：流域面积和主沟比降确定为影响泥石流扇平面形态和面积的最重要的因素。  相似文献