scholarly journals Exponentially Fitted Element-Free Galerkin Approach for Nonlinear Singularly Perturbed Problems

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Jagbir Kaur ◽  
Vivek Sangwan

As it is well recognized that conventional numerical schemes are inefficient in approximating the solutions of the singularly perturbed problems (SPP) in the boundary layer region, in the present work, an effort has been made to propose a robust and efficient numerical approach known as element-free Galerkin (EFG) technique to capture these solutions with a high precision of accuracy. Since a lot of weight functions exist in the literature which plays a crucial role in the moving least square (MLS) approximations for generating the shape functions and hence affect the accuracy of the numerical solution, in the present work, due emphasis has been given to propose a robust weight function for the element-free Galerkin scheme for SPP. The key feature of nonrequirement of elements or node connectivity of the EFG method has also been utilized by proposing a way to generate nonuniformly distributed nodes. In order to verify the computational consistency and robustness of the proposed scheme, a variety of linear and nonlinear numerical examples have been considered and L ∞ errors have been presented. Comparison of the EFG solutions with those available in the literature depicts the superiority of the proposed scheme.

2012 ◽  
Vol 166-169 ◽  
pp. 3237-3240
Author(s):  
Dzulkarnain Ahmad ◽  
Airil Yasreen Mohd Yassin ◽  
Ahmad Kueh

Partial interaction between two different materials of composite beam is consequent from longitudinal slip and transverse uplift effects at interfacial surface. The behaviour has yielded higher order differential equation as compared to beam that interacts fully. In this paper, a meshless approach for the analysis of composite beam with partial interaction by Element Free Galerkin (EFG) method is formulated and investigated. Discretized solely by nodes, the Moving Least Square (MLS) method is adopted for the EFG shape functions formulation and the variational approach is chosen in developing its Galerkin weak form. The weak form essential boundary conditions are enforced by Lagrange multiplier, where comparable results are obtained between developed EFG code and established analytical solutions. In addition, influence of various weight functions on shape function smoothness of EFG code is explored.


2009 ◽  
Vol 06 (03) ◽  
pp. 349-360
Author(s):  
K. SANDEEP ◽  
K. KAMAL KUMAR

The paper presents application of a B-spline function in place of a shape function obtained by using moving least square approximant with B-spline weight and linear basis. The piecewise polynomial function of B-spline with C2 and lower order continuity is efficiently used in element free Galerkin (EFG) method to generate a new fast algorithm for the solution of one-dimensional partial differential equation. The support of B-spline function is assumed as the domain of influence of EFG method. The results of bar deflection are compared with those obtained by other researchers.


2020 ◽  
Vol 12 (08) ◽  
pp. 2050096
Author(s):  
Guodong Zheng ◽  
Yumin Cheng

By using the improved moving least-square (IMLS) approximation to present the shape function, the improved element-free Galerkin (IEFG) method is investigated to solve diffusional drug release problems in this paper. In order to get the discretized equation system, Galerkin weak form of a diffusional drug release problem is used with applying essential boundary conditions using the penalty method. The difference method is applied for discretization of time domain. Then the formulae of IEFG method for solving diffusional drug release problems are presented. Three numerical example problems are given to study the convergence of solutions of IEFG method in this paper. The influences of scale parameters of influence domain, penalty factor and node distribution on the accuracy of the solutions of IEFG method are discussed. Compared with finite element method, the correctness of IEFG method in this paper is shown.


2007 ◽  
Vol 04 (04) ◽  
pp. 543-565 ◽  
Author(s):  
VILAYSAK SAYAKOUMMANE ◽  
WORSAK KANOK-NUKULCHAI

An Element Free Galerkin Method (EFGM) for the analysis of degenerated shell structures is presented. The method is based on the Moving Kriging (MK) Interpolation function. The properties of the interpolation function possess the Kronecker delta property. With the MK Interpolation function no additional treatment required at the boundary conditions compared with that of using Moving Least Square (MLS) approximation. This deficiency of MLS at boundary condition has been definitely eradicated. The membrane and shear locking in the numerical analysis for degenerated shell problems has been alleviated by using higher order and removed by using quartic order of polynomials. Numerical benchmark examples for shell structures are presented to validate the proposed approach.


2021 ◽  
Vol 12 (4) ◽  
pp. 14-22
Author(s):  
H.T.T. Lan

One of mesh free methods, element free Galerkin method, is presented to analyze the finite beam on elastic foundation. The shape functions are constructed by using the moving least square interpolation based on a set of nodes that are arbitrarily distributed in specified domain. Discrete system equations are derived from the variation form of system equations. Numerical examples of finite beam on elastic foundation are given by establishing Matlab code. The results of this paper demonstrate the effectiveness of the proposed method with small errors compared to analytical solutions. Keywords: mesh free method, element free Galerkin method, moving least square, finite beam, elastic foundation.


2004 ◽  
Vol 01 (02) ◽  
pp. 345-365 ◽  
Author(s):  
P. TONGSUK ◽  
W. KANOK-NUKULCHAI

Following its first introduction, this study further scrutinizes the new type of shape functions for Element-free Galerkin Method (EFGM) based on the Moving Kriging (MK) interpolation. Kriging is a geostatistical method of spatial interpolation. Its basic premise is that every unknown point can be interpolated from known scattered points in its specified neighborhood. This property is ideal for EFGM. Previously, a shortcoming of EFGM based on Moving Least Square (MLS) approximation is associated with its limitation to satisfy essential boundary conditions exactly. With MK interpolation functions, EFGM solution can satisfy essential boundary conditions automatically. Numerical tests on one and two-dimensional elasticity problems have confirmed the effectiveness of MK in addressing this specific shortcoming of EFGM. Furthermore, the study also finds the accuracy of EFGM to be greatly enhanced with the use of MK shape functions.


2005 ◽  
Vol 21 (2) ◽  
pp. 125-129 ◽  
Author(s):  
K.-J. Shen ◽  
J. P. Sheng ◽  
C.-Y. Wang

AbstractElement-free Galerkin method (EFGM) based on moving least-square curve fitting concept is presented and applied to elastic fracture problems. Because no element connectivity data are needed, EFGM is very convenient and effective numerical method for crack growth analysis. This paper is intended as an investigation of crack trajectory for different notch locations under three-point bending test. The initial crack growth angles obtained by element-free Galerkin method in comparison with those obtained by lab test reveal that both results are very close. However, numerical results also show that the location of an original notch can stronger affect the variation of crack path for different increment. The stress intensity factors (SIF) of cracks under three-point bending test with different increment are also investigated by EFGM.


2015 ◽  
Vol 723 ◽  
pp. 181-185
Author(s):  
Xing Hui Cai ◽  
Hong Fu Qiang ◽  
Jiang Ren Lu ◽  
Guo Liang Wang

In this paper, a meshless global element-free Galerkin method is given to obtain the numerical solutions of the coupled equations in the velocity and magnetic field for the unsteady magnetohydrodynamic flow through a straight duct with arbitrary electrical conductivity, that is, from perfectly conducting to insulated duct walls. The moving least-square approximation scheme is employed to construct shape functions. A time stepping method is employed to deal with the time derivatives. Non-uniform background grids and nodes are applied for numerical simulations. Computations are performed for different Hartmann numbers and wall conductivities at different time.


Author(s):  
Mao Sheng ◽  
Gensheng Li ◽  
Subhash Shah

The radius of the influence domain is an important parameter in the weight function and plays an essential role in the accuracy of approximations. A modified method was proposed for determining the radius of influence domain. The modification is that the radius of influence domain is prescribed by the desired amount of support nodes for any point of interest. The advantages of this strategy are the regularity of matrix can be ensured in moving least square approximation and the algorithm is simple and practicable. The modified method was validated by thousands of patch tests in the case of regular and irregular node collocations and Timoshenko beam problem with using random node collocation. Results show that the proposed method performs more capability to handle the arbitrary node collocation than the pre-existing methods. This paper provides an alternative way to determine the radius of influence domain.


1999 ◽  
Vol 21 (4) ◽  
pp. 239-250
Author(s):  
Nguyen Hoai Son ◽  
Nguyen The Quang

The Element Free Galerkin (EFG) method is a mesh less method for solving partial differential equations in which the trial and test functions employed in the discretization process result from moving least square interpolations (weak form of the variation AL principle). In this paper, the EFG method for solving problems in least-statics {1-D, 2-D) is developed and numerically implemented. The present method is a mesh less method, as it does not need a "finite element mesh" and it is only composed by the particles with theirs "compact support" (the influence domain) in the whole domain. Specially, the shape functions are not satisfying the Kronecker delta property, therefore, in this paper, we must enforce the essential boundary conditions by the Lagrangian multipliers method. Finally, several numerical examples are presented to illustrate the performance of the EFG method. The results are compared with the other method (EFM) and also with the analytic solutions. It shows that the EFG method gives the good effectiveness of the proposed error estimator in the global energy norm and the high rates of convergence with the size of the "compact support".


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