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边界拟合坐标法在尾水河道计算中的应用及其验证 被引量:1
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作者 庞志刚 陈璧宏 余平 《水力发电学报》 EI CSCD 北大核心 1997年第1期51-63,共13页
本文讲述应用边界拟合坐标法计算柘溪与丰满水电站尾水河道流场。同时进行了水工模型试验进行验证核对两者吻合很好。说明边界拟合坐标法精度较高。
关键词 边界合坐标 尾水河道 河道 流场
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高精度分数时延滤波器设计的边界拟合Remez算法
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作者 吴桐 闫毅 +2 位作者 王春梅 姚秀娟 陈鼎 《国防科技大学学报》 EI CAS CSCD 北大核心 2017年第5期122-127,共6页
在卫星星间测距模拟信号仿真及实际测试中,为提高测距模拟信号精度和系统可用带宽,提出基于边界拟合Remez算法的高精度分数时延滤波器的设计算法。该算法利用Farrow结构的多项式近似思想,采用多项式拟合Remez算法设计滤波器的冲激响应... 在卫星星间测距模拟信号仿真及实际测试中,为提高测距模拟信号精度和系统可用带宽,提出基于边界拟合Remez算法的高精度分数时延滤波器的设计算法。该算法利用Farrow结构的多项式近似思想,采用多项式拟合Remez算法设计滤波器的冲激响应边界系数,通过多相分解实现分数时延滤波器组。该算法改善了当设计的滤波器阶数较高时冲激响应边界的不连续现象,进而降低了群时延误差,提高了精度。仿真结果表明,该算法设计的滤波器的分数时延精度得到了提高,同时系统可用带宽提高近一倍,实现时需使用的乘法器数目也有明显降低。 展开更多
关键词 测距信号 分数时延滤波器组 REMEZ算 群时延误差 边界合算
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热传导方程反问题的数值解法 被引量:1
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作者 任常青 《四川理工学院学报(自然科学版)》 CAS 2008年第3期28-30,共3页
文章分别应用拟边界法和积分方程方法对一类热传导反问题进行了研究,并通过数值算例验证了方法的有效性.
关键词 拟边界法 正则化 反问题 热传导方程 积分方程方
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NUMERICAL SIMULATION AND ANALYSIS OF HORSESHOE-SHAPED VORTEX IN NEAR-WALL REGION OF TURBULENT BOUNDARY LAYER 被引量:5
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作者 史万里 葛宁 +1 位作者 陈林 唐登斌 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2011年第1期48-56,共9页
The low-Reynolds-number full developed turbulent flow in channels is simulated using large eddy simulation(LES)method with the preconditioned algorithm and the dynamic subgrid-scale model,with a given disturbance in... The low-Reynolds-number full developed turbulent flow in channels is simulated using large eddy simulation(LES)method with the preconditioned algorithm and the dynamic subgrid-scale model,with a given disturbance in inlet boundary,after a short development section.The inlet Reynolds number based on momentum thickness is 670.The computed results show good agreement with direct numerical simulation(DNS),which include root mean square fluctuated velocity distribution and average velocity distribution.It is also found that the staggered phenomenon of the coherent structures is caused by sub-harmonic.The results clearly show the formation and evolution of horseshoe vortex in the turbulent boundary layer,including horseshoe vortex structure with a pair of streamwise vortexes and one-side leg of horseshoe vortex.Based on the results,the development of the horseshoe-shaped coherent structures is analyzed in turbulent boundary layer. 展开更多
关键词 large eddy simulation(LES) horseshoe-shaped vortex turbulent boundary layer coherent structures preconditioned algorithm
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Numerical Simulation for Water Entry of a Wedge at Varying Speed by a High Order Boundary Element Method 被引量:6
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作者 Guoxiong Wu 《Journal of Marine Science and Application》 2012年第2期143-149,共7页
A high order boundary element method was developed for the complex velocity potential problem. The method ensures not only the continuity of the potential at the nodes of each element but also the velocity. It can be ... A high order boundary element method was developed for the complex velocity potential problem. The method ensures not only the continuity of the potential at the nodes of each element but also the velocity. It can be applied to a variety of velocity potential problems. The present paper, however, focused on its application to the problem of water entry of a wedge with varying speed. The continuity of the velocity achieved herein is particularly important for this kind of nonlinear free surface flow problem, because when the time stepping method is used, the free surface is updated through the velocity obtained at each node and the accuracy of the velocity is therefore crucial. Calculation was made for a case when the distance S that the wedge has travelled and time t follow the relationship s=Dtα, where D and α are constants, which is found to lead to a self similar flow field when the effect due to gravity is ignored. 展开更多
关键词 high order boundary element method complex velocity potential fluid/structure impact water entry
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Unstructured Grid Immersed Boundary Method for Numerical Simulation of Fluid Structure Interaction 被引量:2
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作者 明平剑 孙扬哲 +1 位作者 段文洋 张文平 《Journal of Marine Science and Application》 2010年第2期181-186,共6页
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 ... 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. 展开更多
关键词 fluid structure interaction immersed boundary method VOS unstructured grids finite volume method
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Multigrid fictitious boundary method for incompressible viscous flows around moving airfoils
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作者 WAN De-Cheng 《Journal of Marine Science and Application》 2007年第2期51-58,共8页
In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NAC... In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carded on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils. 展开更多
关键词 AIRFOILS induced-motion fictitious boundary method FEM MULTIGRID
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Numerical Simulation of the Flow around Two-dimensional Partially Cavitating Hydrofoils 被引量:2
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作者 Fahri Celik Yasemin Arikan Ozden Sakir Bal 《Journal of Marine Science and Application》 2014年第3期245-254,共10页
In the present study, a new approach is applied to the cavity prediction for two-dimensional (2D) hydrofoils by the potential based boundary element method (BEM). The boundary element method is treated with the so... In the present study, a new approach is applied to the cavity prediction for two-dimensional (2D) hydrofoils by the potential based boundary element method (BEM). The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by usethe of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code (FLUENT). Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others. 展开更多
关键词 boundary element method (BEM):sheet cavitation CFD HYDROFOIL cavity closure model 2D hydrofoils
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Iterative Method on Well Bore Boundary in Numerical Modeling of Variably Saturated Flow
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作者 王俊 黄岁樑 Chiu on Ng 《Transactions of Tianjin University》 EI CAS 2012年第2期104-111,共8页
An iterative method was developed for incorporating the well bore boundary into the finite difference model of water flow in variably saturated porous media. Six cases were presented involving groundwater pumping or i... An iterative method was developed for incorporating the well bore boundary into the finite difference model of water flow in variably saturated porous media. Six cases were presented involving groundwater pumping or injection to demonstrate the advantages of the iterative method over the traditional method. For the iterative method, the total flux gradually approached the well discharge and the flux profile was non-uniform. And the iterative method took into account the variation of well bore water table. Compared to the traditional method, the iterative method can simulate the variably saturated flow caused by pumping or injection more realistically. 展开更多
关键词 iterative method variably saturated flow well bore boundary flux profile
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3D Numerical Modeling of Wave Forces on Tandem Fixed Cylinders Using the BEM 被引量:1
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作者 Mohammad Javad Ketabdari Mohammad Mahdi Abaiee Ali Ahmadi 《Journal of Marine Science and Application》 2013年第3期279-285,共7页
In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders.The fluid was considered to be inviscid and irrotational.Therefore,the Helmholtz ... In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders.The fluid was considered to be inviscid and irrotational.Therefore,the Helmholtz equation was used as a governing equation.The boundary element method(BEM) was adopted to discretize the relevant equations.Open boundaries were used in far fields of the study domain.Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them.Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders,ka and kd on forces and trapped modes.The middle cylinder wave forces and trapped modes in a set of nine tandem cylinders were validated utilizing analytical data.The comparisons confirm the accuracy of the model.The results of the inline wave force estimation on n tandem cylinders show that the critical cylinder in the row is the middle one for odd numbers of cylinders.Furthermore the results show that the critical trapped mode effect occurs for normalized cylinder radiuses close to 0.5 and 1.0.Finally the force estimation for n tandem cylinders confirms that force amplitude of the middle cylinder versus normalized separation distance fluctuates about that of a single cylinder. 展开更多
关键词 tandem cylinders boundary element method(BEM) wave force DIFFRACTION trapped mode Henkel function
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An element-free Galerkin method for ground penetrating radar numerical simulation 被引量:2
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作者 冯德山 郭荣文 王洪华 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第1期261-269,共9页
An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different fr... An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different from element-based numerical methods, this approach makes nodes free from the elemental restraint and avoids the explicit mesh discretization. First, we derived the boundary value problem for the 2D GPR simulation problems. Second, a penalty function approach and a boundary condition truncated method were used to enforce the essential and the absorbing boundary conditions, respectively. A three-layered GPR model was used to verify our element-free approach. The numerical solutions show that our solutions have an excellent agreement with solutions of a finite element method(FEM). Then, we used the EFGM to simulate one more complex model to show its capability and limitations. Simulation results show that one obvious advantage of EFGM is the absence of element mesh, which makes the method very flexible. Due to the use of MLS fitting, a key feature of EFM, is that both the dependent variable and its gradient are continuous and have high precision. 展开更多
关键词 element-free Galerkin method moving least-squares method ground penetrating radar forward simulation
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Study of numerical simulation on dual-frequency IP method with FEM 被引量:2
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作者 LIN Jiayong DIN Maobin +1 位作者 TANG Jingtian YAN Hong 《Global Geology》 2010年第2期99-103,共5页
Using the finite element method and Cole-Cole model for dual-frequency IP method to research numerical simulation, the authors introduced the fundamental principle of the dual-frequency IP method and the boundary valu... Using the finite element method and Cole-Cole model for dual-frequency IP method to research numerical simulation, the authors introduced the fundamental principle of the dual-frequency IP method and the boundary value problem and variational equations, then replaced the complex resistivity of the model with the Cole-Cole model's parameters under ignoring the EM effect. Through solving the last linear equations, electric potentials of all the model's points were obtained. With changing model's parameters, the authors got different curves of the Fs and phases. According to the results of the simulation, the algorithm is proved to be correct and adaptable. 展开更多
关键词 dual-frequency IP numerical simulation frequency domain FEM
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Calculation of Turbulent Flow with Pseudo-spectral Method
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作者 梁志勇 谢峰 张根宝 《Journal of Donghua University(English Edition)》 EI CAS 2009年第3期329-332,共4页
This paper deals with the numerical simulation of incompressible turbulent boundary flow of a flat plate with the pseudo-spectral matrix method. In order to appear more than 10 nodes in the turbulent base-stratum and ... This paper deals with the numerical simulation of incompressible turbulent boundary flow of a flat plate with the pseudo-spectral matrix method. In order to appear more than 10 nodes in the turbulent base-stratum and transition of 43×43 computational grids,a coordinate transformation is put up from physical panel to computational panel. Several zero turbulent models are computed comparatively. The results are credible when comparing with the previous methods. 展开更多
关键词 pseudo-spectral method flat plate turbulent flow CALCULATION
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Numerical Investigation of an Oscillating Airfoil using Immersed Boundary Method 被引量:5
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作者 Guohua Zhong Lin Du Xiaofeng Sun 《Journal of Thermal Science》 SCIE EI CAS CSCD 2011年第5期413-422,共10页
Based on the immersed boundary method, a numerical simulation for an oscillating airfoil is established and a preliminary analysis of the oscillating airfoil is presented with an emphasis on the physical understanding... Based on the immersed boundary method, a numerical simulation for an oscillating airfoil is established and a preliminary analysis of the oscillating airfoil is presented with an emphasis on the physical understanding of fluid-structure interaction. In order to validate the method, two simulation cases: oscillating circular cylinder at low K-C number and two degrees of freedom oscillating cylinder are carded out first and the results are in good agreement with the previous re:searches. In the oscillating airfoil simulation, it is found that the reduced velocity U^*. is a very sensitive factor and especially U^*-2.8 is the critical stable boundary in the present work. The method shows the predominance of time saving in computational process for such a complicated fluid-structure interac- tion problem. 展开更多
关键词 TURBOMACHINERY IB method fluid-structure interaction.
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Simulation of Unsteady Flows with Fluctuating Inflow or Outflow Boundary Conditions
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作者 Jianjun Liu Guanghui ZhongInstitute of Engineering Thermophysics, Chinese Academy of Sciences, P.O. Box 2706, Beijing 100080, China 《Journal of Thermal Science》 SCIE EI CAS CSCD 2003年第2期162-166,共5页
This paper describes the numerical simulation of unsteady flows due to incoming wakes and/or varying back pressure,The solution method is based upon the one-step finite-volume TVD Lax-Wendroff scheme.Dual time-step ap... This paper describes the numerical simulation of unsteady flows due to incoming wakes and/or varying back pressure,The solution method is based upon the one-step finite-volume TVD Lax-Wendroff scheme.Dual time-step approach and multigrid algorithm are adopted to improve the computational efficiency of the baseline scheme.Numerical results for the transonic unsteady flow in a channel bump and the unsteady flow in a flat plate cascade and the VKI cascade are presented. 展开更多
关键词 numerical simulation unsteady flow fluctuating boundary conditions.
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