检索结果-南通市图书馆

THE boundary integral METHOD FOR THE HELMHOLTZ equation WITH CRACKS INSIDE A BOUNDED DOMAIN

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2015年第3期35卷 539-551页

作者：郭军范丽丽严国政 School of Mathematics and Statistics South-Central University for Nationalities School of Mathematics and Computer Science Wuhan Polytechnic University School of Mathematics and Statistics Central China Normal University

We consider a kind of scattering problem by a crack F that is buried in a bounded domain D, and we put a point source inside the domain D. This leads to a mixed boundary value problem to the Helmholtz equation in the domain D with a crack Г. Both sides of the crack F are given Dirichlet-impedance boundary conditions, and different boundary condition （Dirichlet, Neumann or Impedance boundary condition） is set on the boundary of D. Applying potential theory, the problem can be reformulated as a system of boundary integral equations. We establish the existence and uniqueness of the solution to the system by using the Fredholm theory.

关键词： boundary integral equation Helmholtz equation Fredholm theory

boundary integral equation——INVERSE METHOD FOR FREE SURFACE GRAVITY FLOWS

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 1987年第9期 992-1008页

作者：温贤云吴持恭 Chengdu University of Science and Technology College of Water Conservancy and Hydroelectric Power

The principal purpose of this paper is to develop a new method for 2-dimensional gravity-influenced free surface potential flows passing arbitrary curvilinear solid boundaries. Using Muskhelishvili’s theory, and by substitution, we can obtain a system of nonsingular boundary-integral equations in the physical plane. The integral equations are solved by an iterative method in which the length of streamline of the boundary is taken as an independent variable, and the velocity potential on boundary as the function to be solved. The difficulties encountered in applying the analytical function theory have been overcome. The analytical theory has found new applications. Theoretical research and numerical calculations indicate that the method is superior to the existing numerical ones in good and fast convergence and small calculating quantity. The free jets flowing through a spillway flip bucket and flows from sluice gates are calculated. The numerical results agree well with those measured.

关键词： INVERSE METHOD FOR FREE SURFACE GRAVITY FLOWS boundary integral equation 刃一一甲 length

A NEW boundary integral equation FOR PLANE HARMONIC FUNCTIONS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1987年第4期3卷 335-343页

作者： Shen Xinzhuo Hu Haichang Department of Mechanics,Peking University Department of Mechanics Peking University Peking China

In this paper,we propose a new boundary integral equation for plane harmonic functions.Asa new approach,the equation is derived from the conservation integrals.Every variable in the integralequation has direct engineering interest.When this integral equation is applied to the Dirichlet problem,onewill get an integral equation of the second kind,so that the algebraic equation system in the boundaryelement method has diagonal dominance.Finally,this equation is applied to elastic torsion problems ofcylinders of different sections,and satisfactary numerical results are obtained.

关键词： harmonic function boundary integral equation conservation integral

Solution of stress intensity factors of multiple cracks in plane elasticity with eigen COD formulation of boundary integral equation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Shanghai University(English Edition) 2011年第3期15卷 173-179页

作者：郭钊马杭 Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Department of Mechanics College of Sciences Shanghai University

The concept of eigen crack opening displacement （COD） can be defined as the COD of a crack in infinite plate under the tractions acting on the crack surface. By introducing this concept, the eigen COD formulation of boundary integral equation is proposed in this paper, together with the solution procedures for multiple crack problems in plane elasticity. With the proposed approach, the multiple crack problems can be solved with the conventional displacement discontinuity boundary integral equations in an iterative fashion with a small size of system matrix as that in the numerical Green’s function （NGF） approach but without the trouble to determine the complementary solutions since the standard boundary element discretization on the crack surface is no longer required with the proposed approach. Some numerical examples computing the stress intensity factors are presented and compared with those in literature to show the accuracy and the effectiveness of the proposed approach.

关键词： crack opening displacement （COD） multiple cracks stress intensity factor boundary integral equation iteration

ON THE UNIQUENESS OF boundary integral equation FOR THE EXTERIOR HELMHOLTZ PROBLEM

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 1990年第10期11卷 965-971页

作者：王清徐博侯 Department of Civil Engineering Zhejiang University Hangzhou Department of Mechanics Zhejiang University Hangzhou

From the point of view of energy analysis, the cause that the uniqueness of the boundary integral equation induced from the exterior Helmholtz problem does not hold is investigated in this paper. It is proved that the Sommerfeld's condition at the infinity is changed so that it is suitable not only for the radiative wave but also for the absorptive wave when we use the boundary integral equation to describe the exterior Helmholtz problem. There fore, the total energy of the system is conservative. The mathematical dealings to guarantee the uniqueness are discussed based upon this explanation.

关键词： exterior Helmholtz problem boundary integral equation uniqueness

A boundary integral equation AND ITS NUMERICAL SOLUTION OF POTENTIAL FLOW AROUND SURFACE-IRREGULA-RITIES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1993年第1期5卷 70-81页

作者： Guo Ya-kun Wen Xian-yun Institute of Hydraulic Research,Chengdu University of Science and Technology,Chengdu,610065,P.R.China

In this paper,using complex functional theory,the authors turn the potential flow around the surface irregularities in a pressure conduit and semi-infinite platforms into Dirichlet problem.Based on Schwarz formula and by the application of Plemelj's formula,the authors change the problem into the integration of a Cauchy boundary integral equation in the flow plane through the substitution of variables.Using numerical integration,the authors obtain the velocity distribution and pressure coefficient along surface irregularities and platforms.The physical concept of this method is clear,the convergent speed is rapid and the computative effi- ciency is high.The calculated values agree well with the measured results.It is an effective and simple method in solving potential flow.

关键词： potential flow boundary integral equation numerical integration

Numerical solution of multiple hole problem by using boundary integral equation

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2011年第3期1卷 27-29页

作者： Yizhou Chen~(a)) Division of Engineering Mechanics,Jiangsu University,Zhenjiang 212013,China Division of Engineering Mechanics Jiangsu University Zhenjiang 212013 China

This paper studies a numerical solution of multiple hole problem by using a boundary integral equation.The studied problem can be considered as a supposition of many single hole problems.After considering the interaction among holes,an algebraic equation is formulated,which is then solved by using an iteration technique.The hoop stress around holes can be finally determined. One numerical example is provided to check its accuracy.

关键词： boundary integral equation iteration multiple holes stress concentration factors

预测规则波浪中船舶运动和载荷的频域三维计算机程序

在线全文

学校读者我要写书评

暂无评论

哈尔滨工程大学学报（英文版） 2024年第1期23卷 64-73页

作者： Arash Abbasnia Serge Sutulo C.Guedes Soares Centre for Marine Technology and Engineering(CENTEC) Instituto Superior TécnicoUniversidade de Lisboa1049-001 LisboaPortugal

The development of an in-house computer program for determining the motions and loads of advancing ships through sea waves in the frequency domain,is described in this paper.The code is based on the potential flow formulation and originates from a double-body code enhanced with the regular part of the velocity potential computed using the pulsing source Green function.The code is fully developed in C++language with extensive use of the object-oriented paradigm.The code is capable of estimating the excitation and inertial radiation loads or arbitrary incoming wave frequencies and incidence angles.The hydrodynamic responses such as hydrodynamic coefficients,ship motions,the vertical shear force and the vertical bending moment are estimated.A benchmark container ship and an LNG carrier are selected for testing and validating the computer code.The obtained results are compared with the available experimental data which demonstrate the acceptable compliance for the zero speed whereas there are some discrepancies over the range of frequencies for the advancing ship in different heading angles.

关键词： Frequency domain Advancing ships Diffraction theory Pulsing green’s function boundary integral equation

boundary integral equationS FOR ISOTROPIC LINEAR ELASTICITY

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2022年第6期40卷 835-864页

作者： Benjamin Stamm Shuyang Xiang Department of Mathematics RWTH Aachen UniversityAachenGermany

This articles first investigates boundary integral operators for the three-dimensional isotropic linear elasticity of a biphasic model with piecewise constant Lam´e coefficients in the form of a bounded domain of arbitrary shape surrounded by a background material.In the simple case of a spherical inclusion,the vector spherical harmonics consist of eigenfunctions of the single and double layer boundary operators and we provide their spectra.Further,in the case of many spherical inclusions with isotropic materials,each with its own set of Lam´e parameters,we propose an integral equation and a subsequent Galerkin discretization using the vector spherical harmonics and apply the discretization to several numerical test cases.

关键词： Isotropic elasticity boundary integral equation Spherical inclusions Vector spherical harmonics Layer potentials