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A Lifting Line Theory for a Three-dimensional Hydrofoil 被引量:1
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作者 梁辉 宗智 《Journal of Marine Science and Application》 2011年第2期199-205,共7页
Prandtl’s lifting line theory was generalized to the lifting problem of a three-dimensional hydrofoil in the presence of a free surface. Similar to the classical lifting theory, the singularity distribution method wa... Prandtl’s lifting line theory was generalized to the lifting problem of a three-dimensional hydrofoil in the presence of a free surface. Similar to the classical lifting theory, the singularity distribution method was utilized to solve two-dimensional lifting problems for the hydrofoil beneath the free surface at the air-water interface, and a lifting line theory was developed to correct three-dimensional effects of the hydrofoil with a large aspect ratio. Differing from the classical lifting theory, the main focus was on finding the three-dimensional Green function of the free surface induced by the steady motion of a system of horseshoe vortices under the free surface. Finally, numerical examples were given to show the relationship between the lift coefficient and submergence Froude numbers for 2-D and 3-D hydrofoils. If the submergence Froude number is small free surface effect will be significant registered as the increase of lift coefficient. The validity of these approaches was examined in comparison with the results calculated by other methods. 展开更多
关键词 lifting line theory singularity distribution method 3-D hydrofoil free surface Green function
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A new method of mesh simplification for 3-Dimension terrain using Laplace operator 被引量:1
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作者 Zuo Wenpin Che Xiangjiu 《Computer Aided Drafting,Design and Manufacturing》 2012年第1期44-48,共5页
This paper proposes a new method to simplify mesh in 3D terrain. The 3D terrain is presented by digital elevation model. First, Laplace operator is introduced to calculate sharp degree of mesh point, which indicates t... This paper proposes a new method to simplify mesh in 3D terrain. The 3D terrain is presented by digital elevation model. First, Laplace operator is introduced to calculate sharp degree of mesh point, which indicates the variation trend of the terrain. Through setting a critical value of sharp degree, feature points are selected. Second, critical mesh points are extracted by an recursive process, and constitute the simplified mesh. Third, the algorithm of linear-square interpolation is employed to restore the characteris- tics of the terrain. Last, the terrain is rendered with color and texture. The experimental results demonstrate that this method can compress data by 16% and the error is lower than 10%. 展开更多
关键词 3-dimension terrain critical mesh point simplified mesh Laplace operator
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NUMERICAL MODELLING OF THREE-DIMENSION CHARACTERISTICS OF WIND-DRIVEN CURRENT IN THE BOHAI SEA 被引量:5
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作者 赵进平 侍茂崇 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1993年第1期70-79,共10页
Three- dimension (3-D) wind-driven currents in the Bohai Sea in both winter and summer are calculated by using a 3- D barotropic steady model, and the results are consistent with observed flow char -acteristics. Based... Three- dimension (3-D) wind-driven currents in the Bohai Sea in both winter and summer are calculated by using a 3- D barotropic steady model, and the results are consistent with observed flow char -acteristics. Based on the results, 3- D characteristics of flow, currents at different depths, compensated flow in the lower layer , long and narrow alongshore current, the area of upwelling and downwelling, main circulation in vertical profile, and the current in Bohai Strait are discussed. 展开更多
关键词 the Bohai Sea- 3-dimension model NUMERICAL study WIND-DRIVEN CURRENT
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3-D段涡的兴波数值计算
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作者 廖浔莉 李国安 叶恒奎 《华中科技大学学报(自然科学版)》 EI CAS CSCD 北大核心 2003年第10期88-89,共2页
基于段涡的线性兴波理论分析 ,给出了段涡的线性兴波速度势和自由表面波形的计算公式 ,提供了数值计算方法并且给出了相应的数值计算结果 .由计算结果可以看出段涡兴波的自由表面形状特征与段涡的长短、段涡离自由表面的距离的关系以及... 基于段涡的线性兴波理论分析 ,给出了段涡的线性兴波速度势和自由表面波形的计算公式 ,提供了数值计算方法并且给出了相应的数值计算结果 .由计算结果可以看出段涡兴波的自由表面形状特征与段涡的长短、段涡离自由表面的距离的关系以及来流速度的大小对段涡兴波的影响 ,为水翼的兴波问题的计算提供了基础 . 展开更多
关键词 兴波理论 自由表面波形 3-D段涡 水翼
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3-dimensional slope stability analyses using non-associative stress-strain relationships 被引量:4
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作者 CHEN ZuYu SUN Ping +1 位作者 WANG YuJie ZHANG HongTao 《Science China(Technological Sciences)》 SCIE EI CAS 2009年第9期2517-2527,共11页
The research work presented in this paper refers to a new slope stability analysis method used for landslide risk evaluations. It is an extension of the 3-dimensional upper-bound slope stability analysis method propos... The research work presented in this paper refers to a new slope stability analysis method used for landslide risk evaluations. It is an extension of the 3-dimensional upper-bound slope stability analysis method proposed by Chen et al. in 2001,which employs the Mohr-Coulomb's associative flow rule. It has been found that in a 3-dimensional area,a prism may not be able to move at friction angles to all its surrounding interfaces,as required by this associative rule,and convergence problems may occasionally arise. The new method establishes two velocity fields:(i) The plastic one that represents a non-associative and the best representative dilation behavior,and (ii) the virtual one that permits the solution for factor of safety in the work and energy balance equation. The new method can then allow any input value of dilation angle and thus solve the convergence problem. A practical application to a concrete dam foundation is illustrated. 展开更多
关键词 non-associative flow RULE SLOPE stability limit analysis 3-dimension
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近自由面三维水翼的水动力分析及试验研究 被引量:3
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作者 陈庆任 叶恒奎 +2 位作者 杨向晖 冯大奎 管延敏 《船舶力学》 EI 北大核心 2011年第10期1115-1120,共6页
采用面元法对近自由面三维水翼进行势流数值分析并进行了相关试验研究。在数值计算中,将Rankine源和偶极子置于边界面上,用时间步进法模拟水翼的势流场和自由表面波形。在自由面采用非线性自由面边界条件,在尾涡面上采用偶极子布置以满... 采用面元法对近自由面三维水翼进行势流数值分析并进行了相关试验研究。在数值计算中,将Rankine源和偶极子置于边界面上,用时间步进法模拟水翼的势流场和自由表面波形。在自由面采用非线性自由面边界条件,在尾涡面上采用偶极子布置以满足Kutta条件。文中给出了数值计算模型的参数,对于不同浸深、不同航速和不同攻角下的水翼,计算了水翼表面上的压力分布,水翼的阻力和升力及自由表面波形。数值计算结果与试验结果进行了对比。结果表明,文中方法可用于水翼优化设计、近自由面振动翼运动及水翼船兴波等问题的研究。 展开更多
关键词 自由面 三维水翼 RANKINE源 偶极子 时间步进法 水动力试验
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近自由面三维水翼的水动力时域分析(英文) 被引量:3
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作者 陈庆任 叶恒奎 管延敏 《船舶力学》 EI 北大核心 2010年第12期1331-1339,共9页
基于格林定理,将Rankine源和偶极子置于边界面上,用时间步进法计算了近自由面条件下的三维水翼的势流场。其中在自由面采用线性自由面边界条件,在尾涡面上采用偶极子布置以满足Kutta条件。影响系数中的奇异积分及非奇异积分都采用一种... 基于格林定理,将Rankine源和偶极子置于边界面上,用时间步进法计算了近自由面条件下的三维水翼的势流场。其中在自由面采用线性自由面边界条件,在尾涡面上采用偶极子布置以满足Kutta条件。影响系数中的奇异积分及非奇异积分都采用一种精确积分的方法计算。文中确定了计算模型和参数,给出了不同航速、展长及浸深下的数值计算结果,并与相关文献结果进行了对比,证实了该方法是一种可靠、有效的时域算法。 展开更多
关键词 三维水翼 自由面 RANKINE源 偶极子 时域 精确积分
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粘性流中的近水面三维水翼水动力特性数值分析 被引量:1
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作者 谢宜 郑义 《海军工程大学学报》 CAS 北大核心 2011年第2期22-26,35,共6页
采用有限体积法、RNGk-ε湍流模式对二维及三维水翼近水面航行水动力进行了数值模拟,并与模型试验结果进行了比较分析。结果表明:当水翼浸深与弦长之比大于1时,数值计算方法与试验结果一致,且三维计算精度略高于二维。初步研究了NACA241... 采用有限体积法、RNGk-ε湍流模式对二维及三维水翼近水面航行水动力进行了数值模拟,并与模型试验结果进行了比较分析。结果表明:当水翼浸深与弦长之比大于1时,数值计算方法与试验结果一致,且三维计算精度略高于二维。初步研究了NACA2410水翼在粘性流中近水面航行时升力、阻力特性随攻角、浸深、速度变化的规律,指出该型水翼以Fnc=1.65在近水面航行时有利攻角约为6°、浸深比小于1时,随着傅汝德数的增大,水翼的升力表现出强非线性。 展开更多
关键词 三维水翼 自由水面 浸深 有限体积法
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THE DIVERGENCE-CONVERGENCE EFFECT OF SURFACE CURRENT AND ITS ACTION ON THE BOHAI SEA
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作者 赵进平 侍茂崇 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1993年第2期135-142,共8页
The action of the wind field and the influence of topography can cause divergence or convergence of surface current. The existence of the divergence-convergence effect is proved and the dynamical significance of the d... The action of the wind field and the influence of topography can cause divergence or convergence of surface current. The existence of the divergence-convergence effect is proved and the dynamical significance of the divergent or convergent state and its link with many marine phenomena are pointed out. Divergence fields of surface current in the Bohai Sea in winter and summer are obtained by numerical modelling describing the divergence-convergence character of seasonally wind-driven current. The relation between the effect and seasonal marine phenomena is discussed. Study on the divergence-convergence effect of surface current (DCESC)can be an indirect method for testing the calculated results. 展开更多
关键词 DIVERGENCE divergence-convergence effect SURFACE CURRENT the Bohai SEA 3-dimension model
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Controlling Unstable Discrete Chaos and Hyperchaos Systems
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作者 Xin Li Suping Qian 《Applied Mathematics》 2013年第11期1-6,共6页
A method is introduced to stabilize unstable discrete systems, which does not require any adjustable control parameters of the system. 2-dimension discrete Fold system and 3-dimension discrete hyperchaotic system are ... A method is introduced to stabilize unstable discrete systems, which does not require any adjustable control parameters of the system. 2-dimension discrete Fold system and 3-dimension discrete hyperchaotic system are stabilized to fixed points respectively. Numerical simulations are then provided to show the effectiveness and feasibility of the proposed chaos and hyperchaos controlling scheme. 展开更多
关键词 2-dimension DISCRETE FOLD SYSTEM 3-dimension DISCRETE HYPERCHAOTIC SYSTEM LYAPUNOV Stability Theory Controlling Chaos
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Discussion on design for alkaline cleaning system of continual annealing line
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作者 HE Daohong,YI Fan and LU Zhiyi Baosteel Engineering & Technology Group Co.,Ltd.,Shanghai 201900 《Baosteel Technical Research》 CAS 2010年第S1期117-,共1页
Conventional process flow and main work mechanism of alkaline cleaning process of Continual Annealing Line are generally reviewed in the paper,and the work flow of design is analysed including the lye,rinse water circ... Conventional process flow and main work mechanism of alkaline cleaning process of Continual Annealing Line are generally reviewed in the paper,and the work flow of design is analysed including the lye,rinse water circuit,conductivity detection circuit,utility media supply circuit and other main working circuits.Meanwhile,the heat demand of the alkaline cleaning system,rinse water system and dryer device are also analysed.Lumped parameter method in the heat-transfer theory is adopted to calculate the heating time of unsteady heat transfer for strips in the on-line tank.And the reasons why brush roller is of inverse brush and rinsing nozzles are equipped at the inlet side are found.Types and working principles of iron removal and degreasing devices for alkaline cleaning system,which adopt new magnetic filtration and ultra filtration processes,are described.Besides,the bypass filtering method is used to calculate the processing capacity of magnetic filtration and ultra filtration devices.Finally,the related features of 3-Dimension software "PlantSpace" for designing a CAL in Baosteel are totally introduced,such as specification for piping,co-designing,pipe code and 3-Dimension design process. 展开更多
关键词 alkaline cleaning heating time magnetic filtration ultra filtration 3-dimension design
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A Study of Transform Encoding Using Frequency Spectrum Selection in 3D-DCT for Sequence Image 被引量:1
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作者 WANGShi-gang CHENHe-xin 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2001年第3期34-38,共5页
This paper puts forward the concept of laminar e ncoding based on frequency spectrum selection in 3D-DCT of sequence image. And the pattern of laminar encoding is suitable for the demands of the development of current... This paper puts forward the concept of laminar e ncoding based on frequency spectrum selection in 3D-DCT of sequence image. And the pattern of laminar encoding is suitable for the demands of the development of current communication. So this method is very useful in video communication and has wide prospect. 展开更多
关键词 image encode 3-dimensioned Discrete Cosine Transform (3D-DCT) transform encoding frequency spectrum selection
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NUMERICAL SIMULATIONS OF CAVITATING FLOWS 被引量:9
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作者 Ph.D.Candidate:Wu Lei School of Civil Engineering and Mechanics, Shanghai Jiaotong University, Shanghai 200240, China Supervisor:Lu Chuan-jing (Shanghai Jiaotong University) Xue Lei ping (Shanghai Jiaotong University) Members of Dissertation Defense Committee:Dong Shi-tang (China Ship Scientific Research Center),Chairman Dai Shi-qiang (Shanghai University) Zhang Hui-sheng (Fudan University) Miao Guo-ping (Shanghai Jiaotong Universi ty) He You-sheng (Shanghai Jiaotong University)Liu Hua (Shanghai Jiaotong University) Lu Chuang-jing (Shanghai Jiaotong Universi ty) 《Journal of Hydrodynamics》 SCIE EI CSCD 2003年第4期125-125,共1页
A new model, which involves viscous and multi-phase effects, was given to study cavitating flows. A local compressible model was established by introducing a density-pressure function to account for the two-phase flow... A new model, which involves viscous and multi-phase effects, was given to study cavitating flows. A local compressible model was established by introducing a density-pressure function to account for the two-phase flow of water/vapor and the transition from one phase to the other. An algorithm for calculating variable-density N-S equations of cavitating flow problem was put forward. The present method yields reasonable results for both steady and unsteady cavitating flows in 2D and 3D cases. The numerical results of unsteady character of cavitating flows around hydrofoils coincide well with experimental data. It indicates the feasibility to apply this method to a variety of cavitating flows of practical problems. 展开更多
关键词 two-phase cavitating flow model variable-density N-S equations solver 2D and 3D unsteady cavitating flow periodic cavity break-off and shedding hydrofoil axisymmetric body
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