Boundary Node Method Research Articles

Application of Two Dimensional Extended Boundary Node Method to Potential Problem

The boundary node method has been reformulated without using any integration cells and its performance has been investigated by comparing with the dual reciprocal boundary element method (DRM). The results of computations show that the accuracy of the proposed method is superior to that of the DRM regardless of the number of a boundary node, a boundary condition and a boundary shape. In addition, when the number of boundary nodes exceeds a certain limit, the calculation speed of the proposed method becomes almost equal to that of the DRM.

Three Dimensional Extended Boundary Node Method to Potential Problem

A three-dimensional boundary-node method without any integration cells has been formulated. In the proposed method, an implicit surface is assumed as a surface boundary, and the 3D local coordinates are used to evaluate surface integrals. Numerical experiments illustrate that although the computational costs of the proposed method are larger than those of the boundary element method (BEM), the proposed method enables the evaluation of surface integrals without any integration cells. In addition, the accuracy of the proposed method is almost the same as that of the BEM for the Laplace problem.

Dual reciprocity hybrid boundary node method for acoustic eigenvalue problems

The hybrid boundary node method (HBNM) is a truly meshless method, and elements are not required for either interpolation or integration. The method, however, can only be used for solving homogeneous problems. For the inhomogeneous problem, the domain integration is inevitable. This paper applied the dual reciprocity hybrid boundary node method (DRHBNM), which is composed by the HBNM and the dual reciprocity method (DRM) for solving acoustic eigenvalue problems. In this method, the solution is composed of two parts, i.e. the complementary solution and the particular solution. The complementary solution is solved by HBNM and the particular one is obtained by DRM. The modified variational formulation is applied to form the discrete equations of HBNM. The moving least squares (MLS) is employed to approximate the boundary variables, while the domain variables are interpolated by the fundamental solutions. The domain integration is interpolated by radial basis function (RBF). The Q–R algorithm and Householder algorithm are applied for solving the eigenvalues of the transformed matrix. The parameters that influence the performance of DRHBNM are studied through numerical examples. Numerical results show that high convergence rates and high accuracy are achievable.

Multiple reciprocity hybrid boundary node method for potential problems

Meshless methods have some obvious advantages such as they do not require meshes in the domain and on the boundary, only some nodes are needed in the computation. Furthermore, for the boundary-type meshless methods, the nodes are even not needed in the domain and only distributed on the boundary. Practice shows that boundary-type meshless methods are effective for homogeneous problems. But for inhomogeneous problems, the application of these boundary-type meshless methods has some difficulties and need to be studied further. The hybrid boundary node method (HBNM) is a boundary-only meshless method, which is based on the moving least squares (MLS) approximation and the hybrid displacement variational principle. No cell is required either for the interpolation of solution variables or for numerical integration. It has a drawback of ‘boundary layer effect’, so a new regular hybrid boundary node method (RHBNM) has been proposed to avoid this pitfall, in which the source points of the fundamental solutions are located outside the domain. These two methods, however, can only be used for solving homogeneous problems. Combining the dual reciprocity method (DRM) and the HBNM, the dual reciprocity hybrid boundary node method (DRHBNM) has been proposed for the inhomogeneous terms. The DRHBNM requires a substantial number of internal points to interpolate the particular solution by the radial basis function, where approximation based only on boundary nodes may not guarantee sufficient accuracy. Now a further improvement to the RHBNM, i.e., a combination of the RHBNM and the multiple reciprocity method (MRM), is presented and called the multiple reciprocity hybrid boundary node method (MRHBNM). The solution comprises two parts, i.e., the complementary and particular solutions. The complementary solution is solved by the RHBNM. The particular solution is solved by the MRM, i.e., a sum of high-order homogeneous solutions, which can be approximated by the same-order fundamental solutions. Compared with the DRHBNM, the MRHBNM does not require internal points to obtain the particular solution for inhomogeneous problems. Therefore, the present method is a real boundary-only meshless method, and can be used to deal with inhomogeneous problems conveniently. The validity and efficiency of the present method are demonstrated by a series of numerical examples of inhomogeneous potential problems.

Meshless boundary integral equations with equilibrium satisfaction

A known feature of any mixed interpolation boundary integral equations (BIE)-based methods is that equilibrium is not generally guaranteed in the numerical solution. Here, a complete meshless technique, based on the boundary element-free method (BEFM) with complete equilibrium satisfaction for 2D elastostatic analysis is proposed. The BEFM adopted is a meshless method based on boundary integral equations such as local boundary integral equation (LBIE) method and boundary node method (BNM), differing from them with respect to the integration domain and the approximation scheme.

Meshless analysis of two-dimensional Stokes flows with the Galerkin boundary node method

In this paper, the Galerkin boundary node method (GBNM) is developed for the solution of stationary Stokes problems in two dimensions. The GBNM is a boundary only meshless method that combines a variational form of boundary integral formulations for governing equations with the moving least-squares (MLS) approximations for construction of the trial and test functions. Boundary conditions in this approach are included into the variational form, thus they can be applied directly and easily despite the MLS shape functions lack the property of a delta function. Besides, the GBNM keeps the symmetry and positive definiteness of the variational problems. Convergence analysis results of both the velocity and the pressure are given. Some selected numerical tests are also presented to demonstrate the efficiency of the method.

A hybrid radial boundary node method based on radial basis point interpolation

The hybrid boundary node method (HBNM) retains the meshless attribute of the moving least squares (MLS) approximation and the reduced dimensionality advantages of the boundary element method. However, the HBNM inherits the deficiency of the MLS approximation, in which shape functions lack the delta function property. Thus in the HBNM, boundary conditions are implemented after they are transformed into their approximations on the boundary nodes with the MLS scheme. This paper combines the hybrid displacement variational formulation and the radial basis point interpolation to develop a direct boundary-type meshless method, the hybrid radial boundary node method (HRBNM) for two-dimensional potential problems. The HRBNM is truly meshless, i.e. absolutely no elements are required either for interpolation or for integration. The radial basis point interpolation is used to construct shape functions with delta function property. So unlike the HBNM, the HRBNM is a direct numerical method in which the basic unknown quantity is the real solution of nodal variables, and boundary conditions can be applied directly and easily, which leads to greater computational precision. Some selected numerical tests illustrate the efficiency of the method proposed.

Dual Reciprocity Singular Hybrid Boundary Node Method for Solving Inhomogeneous Equations

AbstractBased on the radial basis function (RBF) and the singular hybrid boundary node method (SHBNM), this paper presents an inherent meshless, boundary-only technique, which names dual reciprocity singular hybrid boundary node method (DRSHBNM), for numerical solution of various inhomogeneous equations. In this study, the RBFs are employed to approximate the inhomogeneous terms via dual reciprocity method (DRM), while the general solution is solved by means of SHBNM, in which only requires discrete nodes constructed on the boundary of a domain, while several nodes in the domain are needed for the RBF interpolation. The treatment of singularity integration and the 'boundary layer effect' have been given by a series of effective approaches. Numerical examples for the solution of inhomogeneous equations show that high convergence rates and high accuracy with a small node number are achievable.

A meshless Galerkin method for Stokes problems using boundary integral equations

A meshless Galerkin scheme for the simulation of two-dimensional incompressible viscous fluid flows in primitive variables is described in this paper. This method combines a boundary integral formulation for the Stokes equation with the moving least-squares (MLS) approximations for construction of trial and test functions for Galerkin approximations. Unlike the domain-type method, this scheme requires only a nodal structure on the bounding surface of a body for approximation of boundary unknowns, thus it is especially suitable for the exterior problems. Compared to other meshless methods such as the boundary node method and the element free Galerkin method, in which the MLS is also introduced, boundary conditions do not present any difficulty in using this meshless method. The convergence and error estimates of this approach are presented. Numerical examples are also given to show the efficiency of the method.

A Galerkin Boundary Node Method for Two-Dimensional Linear Elasticity

A Galerkin Boundary Node Method for Two-Dimensional Linear Elasticity

A boundary face method for potential problems in three dimensions

AbstractThis work presents a new implementation of the boundary node method (BNM) for numerical solution of Laplace's equation. By coupling the boundary integral equations and the moving least‐squares (MLS) approximation, the BNM is a boundary‐type meshless method. However, it still uses the standard elements for boundary integration and approximation of the geometry, thus loses the advantages of the meshless methods. In our implementation, here called the boundary face method, the boundary integration is performed on boundary faces, which are represented in parametric form exactly as the boundary representation data structure in solid modeling. The integrand quantities, such as the coordinates of Gauss integration points, Jacobian and out normal are calculated directly from the faces rather than from elements. In order to deal with thin structures, a mixed variable interpolation scheme of 1‐D MLS and Lagrange Polynomial for long and narrow faces. An adaptive integration scheme for nearly singular integrals has been developed. Numerical examples show that our implementation can provide much more accurate results than the BNM, and keep reasonable accuracy in some extreme cases, such as very irregular distribution of nodes and thin shells. Copyright © 2009 John Wiley & Sons, Ltd.

A Galerkin boundary node method for biharmonic problems

A Galerkin boundary node method (GBNM) is developed in this paper for solving biharmonic problems. The GBNM combines an equivalent variational form of boundary integral formulations for governing equations with the moving least-squares approximations for construction of the trial and test functions. In this approach, only a nodal data structure on the boundary of a domain is required. In addition, boundary conditions can be implemented accurately and the system matrices are symmetric. The convergence of this method and numerical examples are given to show the efficiency.

A Galerkin boundary node method and its convergence analysis

The boundary node method (BNM) exploits the dimensionality of the boundary integral equation (BIE) and the meshless attribute of the moving least-square (MLS) approximations. However, since MLS shape functions lack the property of a delta function, it is difficult to exactly satisfy boundary conditions in BNM. Besides, the system matrices of BNM are non-symmetric. A Galerkin boundary node method (GBNM) is proposed in this paper for solving boundary value problems. In this approach, an equivalent variational form of a BIE is used for representing the governing equation, and the trial and test functions of the variational formulation are generated by the MLS approximation. As a result, boundary conditions can be implemented accurately and the system matrices are symmetric. Total details of numerical implementation and error analysis are given for a general BIE. Taking the Dirichlet problem of Laplace equation as an example, we set up a framework for error estimates of GBNM. Some numerical examples are also given to demonstrate the efficacity of the method.

Dual reciprocity hybrid boundary node method for free vibration analysis

As a truly meshless method of boundary-type, the hybrid boundary node method (HBNM) has the advantages of both boundary element method (BEM) and meshless method. The main problem is that it is only suitable for the homogeneous problems. Now, the dual reciprocity method (DRM) is introduced into HBNM to deal with the integral for the inhomogeneous terms of the governing equations, and the rigid body motion approach is employed to solve the hyper-singular integrations. A new meshless method named dual reciprocity hybrid boundary node method (DRHBNM) is proposed and applied to solve free vibration problems. In this method, the solution composes into two parts, i.e., the general solution and the particular solution. The general solution is solved by HBNM and the particular one is obtained by DRM. DRHBNM is a true boundary-type meshless method. It does not require the ‘boundary element mesh’, either for the purpose of interpolation of the variables, or for the integration of ‘energy’. The points in the domain are only used to interpolate particular solution by the radial basis function. Finally, the boundary variables are interpolated by the independent smooth boundary segments. The Q–R algorithm and Householder algorithm are applied to solve the eigenvalues and eigenvectors of the transformed matrix. Numerical examples for free vibration problems show that a good convergence with mesh refinement is achievable and the computational results for the natural circular frequencies and free vibration modes are very accurate. Furthermore, the computation parameters have little influence on the results and can be chosen in a wide range. It is shown that the present method is effective and can be widely applied in practical engineering.

A meshless hybrid boundary-node method for Helmholtz problems

By coupling the moving least squares (MLS) approximation with a modified functional, the hybrid boundary node-method (hybrid BNM) is a boundary-only, truly meshless method. Like boundary element method (BEM), an initial restriction of the present method is that non-homogeneous terms accounting for effects such as distributed loads are included in the formulation by means of domain integrals, and thus make the technique lose the attraction of its ‘boundary-only’ character. This paper presents a new boundary-type meshless method dual reciprocity-hybrid boundary node method (DR-HBNM), which is combined the hybrid BNM with the dual reciprocity method (DRM) for solving Helmholtz problems. In this method, the solution of Helmholtz problem is divided into two parts, i.e. the complementary solution and the particular solution. The complementary solution is solved by means of hybrid BNM and the particular one is obtained by DRM. The modified variational formulation is applied to form the discrete equations of hybrid BNM. The MLS is employed to approximate the boundary variables, while the domain variables are interpolated by fundamental solutions. The domain integration is interpolated by radial basis function (RBF). The proposed method in the paper retains the characteristics of the meshless method and BEM, which only requires discrete nodes constructed on the boundary of a domain, several nodes in the domain are needed just for the RBF interpolation. The parameters that influence the performance of this method are studied through numerical examples and known analytical fields. Numerical results for the solution of Helmholtz equation show that high convergence rates and high accuracy are achievable.

Dual reciprocity hybrid boundary node method for three-dimensional elasticity with body force

Combining Dual Reciprocity Method (DRM) with Hybrid Boundary Node Method (HBNM), the Dual Reciprocity Hybrid Boundary Node Method (DRHBNM) is developed for three-dimensional linear elasticity problems with body force. This method can be used to solve the elasticity problems with body force without domain integral, which is inevitable by HBNM. To demonstrate the versatility and the fast convergence of this method, some numerical examples of 3-D elasticity problems with body forces are examined. The computational results show that the present method is effective and can be widely applied in solving practical engineering problems.

Dual reciprocity hybrid boundary node method for 2-D elasticity with body force

A boundary-type meshless method named dual reciprocity hybrid boundary node method (DRHBNM) is presented. It can be applied to solve elasticity problems with body force, centrifugal load, or other similar problems. In this method, the solution comprises two parts, i.e., the general solution and the particular solution. The general solution is solved by the hybrid boundary node method (HBNM), and the particular one is obtained by the dual reciprocity method (DRM). This method extends the Kelvin fundamental solution for static elastic problems without body force to non-homogeneous problems with body or inertial forces. A modified variational formulation is applied to form the discrete equations of HBNM. The moving least squares (MLS) are employed to approximate the boundary variables, while the domain variables are interpolated by the classical fundamental solution. The particular solution for the body force is obtained by DRM, and the integration in the domain is interpolated by the radial basis function. The proposed method retains the characteristics of the meshless method. At the same time, it employs the fundamental solution as in the boundary element method (BEM). Therefore, this method has the advantages of both meshless method and BEM. It does not require a ‘boundary element mesh’, either for the purpose of interpolation of the solution variables, or for the integration of the ‘energy’. The points in the domain are used only to interpolate particular solutions by the radial basis function and it is not necessary for the integration and approximation of the solution variables. Finally, the boundary solution variables are interpolated by the independent smooth segment boundary. As special treatments for corners are not required, it can obtain accurate boundary tractions for non-smooth boundaries. Numerical examples of 2-D elasticity problems with body force are used to demonstrate the versatility of the method and its fast convergence. The computational results for unknown variables are accurate. Also, the variable parameters have little influence on the results and can be changed in wide ranges. It is shown that the present method is effective and can be widely applied to practical problems.

Two-dimensional elastostatic analysis of FGMs via BEFM

In this work, a complete meshless technique, based on the Boundary Element-Free Method (BEFM) for 2-D elastostatic analysis applied to Functionally Graded Materials (FGMs) is proposed. FGMs are non-homogenous materials in which some properties (e.g. density, Young modulus, Poisson rate, etc.) vary as a function of spatial coordinates. BEFM is a meshless method based on Boundary Integral Equations (BIE) such as the Local Boundary Integral Equation (LBIE) method and the Boundary Node Method (BNM), differing from them with respect to the integration domain and the approximation scheme.

Numerical Simulation of 3-D Potential Problems by Regular Hybrid Boundary Node Method

The Regular Hybrid Boundary Node Method (RHBNM) is developed for solving three-dimensional potential problems. Formulations are developed and a general computer code written in C++. The RHBNM is formulated in terms of the domain and boundary variables. The domain variables are interpolated by classical fundamental solutions with the source points located outside the domain, and the boundary variables are interpolated by MLS approximation. The main idea is to retain the dimensionality advantages of the Boundary Element Method, and localize the integration domain to a regular sub-domain so that no mesh is needed for integration. All integrals can be easily evaluated over regularly shaped domains (in general, semi-sphere in the 3-D problem) and their boundaries. Numerical examples demonstrate that high convergence rate with mesh refinement and high accuracy with a small node number are achievable.

431 メッシュフリー境界節点法による三次元表面き裂の進展解析(OS10.メッシュフリー/粒子法とその関連技術(7),オーガナイズドセッション)

431 メッシュフリー境界節点法による三次元表面き裂の進展解析(OS10.メッシュフリー/粒子法とその関連技術(7),オーガナイズドセッション)