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  Subjects -> ENGINEERING (Total: 1971 journals)
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ENGINEERING (1117 journals)            First | 1 2 3 4 5 6 7 8 | Last

Developments in Geotechnical Engineering     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 1)
Diálogos Interdisciplinares     Open Access  
Diamond Light Source Proceedings     Full-text available via subscription  
Digital Signal Processing     Hybrid Journal   (Followers: 7)
Discrete Optimization     Full-text available via subscription   (Followers: 4)
Doct-Us Journal     Open Access  
Documents pour l'histoire des techniques     Open Access   (Followers: 1)
Dyes and Pigments     Hybrid Journal   (Followers: 3)
Dyna     Open Access  
Dynamical Systems: An International Journal     Hybrid Journal   (Followers: 1)
El Hombre y la Máquina     Open Access  
Electromagnetics     Hybrid Journal   (Followers: 1)
Electrophoresis     Hybrid Journal   (Followers: 5)
Elsevier Geo-Engineering Book Series     Full-text available via subscription   (Followers: 1)
Elsevier Ocean Engineering Series     Full-text available via subscription  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 18)
Energies     Open Access   (Followers: 2)
Energy and Power Engineering     Open Access   (Followers: 9)
Energy Conversion and Management     Hybrid Journal   (Followers: 7)
Energy Engineering     Full-text available via subscription   (Followers: 9)
Energy for Sustainable Development     Hybrid Journal   (Followers: 9)
Energy Procedia     Open Access   (Followers: 2)
Energy Science & Engineering     Open Access   (Followers: 3)
Energy Science and Technology     Open Access   (Followers: 11)
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects     Hybrid Journal   (Followers: 2)
Energy Sources, Part B: Economics, Planning, and Policy     Hybrid Journal   (Followers: 6)
Energy Systems     Hybrid Journal   (Followers: 9)
ENGEVISTA     Open Access  
ENGI : Revista Electrónica de la Facultad de Ingenieria     Open Access  
Engineer : Journal of the Institution of Engineers, Sri Lanka     Open Access  
Engineering     Open Access   (Followers: 2)
Engineering & Technology     Hybrid Journal   (Followers: 17)
Engineering Analysis with Boundary Elements     Hybrid Journal   (Followers: 1)
Engineering Computations     Hybrid Journal   (Followers: 3)
Engineering Economics     Open Access   (Followers: 4)
Engineering Economist, The     Hybrid Journal   (Followers: 2)
Engineering Education     Open Access  
Engineering Failure Analysis     Hybrid Journal   (Followers: 26)
Engineering Geology     Hybrid Journal   (Followers: 7)
Engineering Journal     Open Access   (Followers: 1)
Engineering Management Journal     Hybrid Journal   (Followers: 12)
Engineering Management Research     Open Access   (Followers: 4)
Engineering Management Reviews     Open Access   (Followers: 1)
Engineering Optimization     Hybrid Journal   (Followers: 6)
Engineering Sciences     Open Access  
Engineering Studies     Hybrid Journal  
Engineering With Computers     Hybrid Journal   (Followers: 5)
Engineering, Technology & Applied Science Research     Open Access  
Entramado     Open Access  
Entropy     Open Access   (Followers: 3)
Environmental & Engineering Geoscience     Full-text available via subscription   (Followers: 2)
Environmental and Ecological Statistics     Hybrid Journal   (Followers: 5)
Environmetrics     Hybrid Journal  
Épités - Épitészettudomány     Full-text available via subscription   (Followers: 1)
EPJ Photovoltaics     Open Access   (Followers: 1)
Épsilon     Open Access  
Ergonomics in Design: The Quarterly of Human Factors Applications     Hybrid Journal   (Followers: 6)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription  
ESAIM: Mathematical Modelling and Numerical Analysis     Full-text available via subscription   (Followers: 2)
ESAIM: Proceedings     Open Access  
Estuaries and Coasts     Hybrid Journal   (Followers: 3)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 1)
European Journal of Engineering Education     Hybrid Journal   (Followers: 1)
European Journal of Lipid Science and Technology     Hybrid Journal   (Followers: 1)
European Journal of Mass Spectrometry     Full-text available via subscription   (Followers: 10)
European Medical Device Technology     Full-text available via subscription   (Followers: 2)
European Physical Journal - Applied Physics     Full-text available via subscription   (Followers: 4)
European Transport Research Review     Open Access   (Followers: 10)
Evolutionary Intelligence     Hybrid Journal  
Evolving Systems     Hybrid Journal  
Exacta     Open Access  
Experimental Techniques     Hybrid Journal   (Followers: 30)
Experiments in Fluids     Hybrid Journal   (Followers: 6)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Filtration & Separation     Full-text available via subscription   (Followers: 2)
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 2)
Fire Science Reviews     Open Access   (Followers: 1)
First Monday     Open Access   (Followers: 185)
Flexible Services and Manufacturing Journal     Hybrid Journal   (Followers: 2)
Flow, Turbulence and Combustion     Hybrid Journal   (Followers: 17)
Fluid Dynamics     Hybrid Journal   (Followers: 5)
Fluid Dynamics Research     Full-text available via subscription   (Followers: 7)
Fluid Phase Equilibria     Hybrid Journal   (Followers: 1)
Focus on Catalysts     Full-text available via subscription  
Focus on Pigments     Full-text available via subscription   (Followers: 4)
Focus on Powder Coatings     Full-text available via subscription   (Followers: 3)
Focus on Surfactants     Full-text available via subscription   (Followers: 3)
Food Engineering Reviews     Hybrid Journal   (Followers: 2)
Food Science and Technology     Open Access  
Formación Universitaria     Open Access   (Followers: 3)
FORMakademisk     Open Access  
Formal Methods in System Design     Hybrid Journal   (Followers: 6)
Forschung     Hybrid Journal  
Forschung im Ingenieurwesen     Hybrid Journal  
Foundations and Trends in Systems and Control     Full-text available via subscription  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
Foundations of Science     Hybrid Journal  
Frontiers in Aerospace Engineering     Open Access   (Followers: 5)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover Engineering Analysis with Boundary Elements
   Journal TOC RSS feeds Export to Zotero [3 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0955-7997
     Published by Elsevier Homepage  [2570 journals]   [SJR: 1.22]   [H-I: 39]
  • Efficient 3D boundary element dynamic analysis of discontinuities
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): M. Ghiasian , M.T. Ahmadi
      In the present study, a nonlinear joint element model with a coupled shear-tensile behavior for multi body boundary element frictional contact problems is presented. The analysis is carried out by discrete crack model using the multi-region 3D boundary element method including material damping. To account for the decay of joint strength parameters at intermediate courses of deformation, the simplified discrete crack joint model (SDCJ) has been used. The nonlinear nature of contact problems demands an iterative technique development to determine the actual contact conditions (opening and sliding with bonding and friction) at arbitrary points of the contact boundaries. Through several analyses, it is demonstrated that the proposed method is robust, as it does not require to solve the whole system simultaneously. As a particular case, the influence of foundation inhomogeneity on the seismic response of concrete arch dam has been studied in order to illustrate the accuracy and efficiency of the present approach in a complicated case.


      PubDate: 2014-10-12T08:04:30Z
       
  • A projection iterative algorithm for the Signorini problem using the
           boundary element method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Shougui Zhang
      This paper proposes a new iterative algorithm for the numerical solution of the Signorini problem for Laplacian using the boundary element method. Since the Signorini boundary conditions are equivalent to a projection fixed point problem, the Signorini boundary conditions can be transformed into a sequence of Dirichlet boundary conditions in a simple iterative manner. Therefore, the algorithm only requires solving a sequence of problems with straightforward boundary conditions. We also investigate the convergence criteria of the algorithm. As the iteration process is given on the Signorini boundary of the domain, the boundary element method is especially suitable for the algorithm. Finally, the numerical results demonstrate the accuracy and validity of the algorithm.


      PubDate: 2014-10-12T08:04:30Z
       
  • An accurate improved complex variable element-free method for numerical
           solutions of elastodynamic problems
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): J.F. Wang , K.M. Liew
      In this paper, an improved complex variable element-free method (ICVEFM) is proposed and implemented for elastodynamic problems. The modeling process involves element-free approximation based on an improved complex variable moving least-squares (ICVMLS) and employs the Galerkin procedure to derive the discretized equation system. Since the best mean-square approximation for both real and imaginary parts is simultaneously achieved, the ICVEFM facilitates a higher computing efficiency. The Newmark-β method for time integration and penalty method for essential boundary conditions are introduced to derive the corresponding formulae. Several numerical examples including free vibration and forced vibration with time history analyses are presented to demonstrate the accuracy of the proposed method, vis-à-vis the analytical and numerical solutions.


      PubDate: 2014-10-12T08:04:30Z
       
  • Numerical solution of stochastic elliptic partial differential equations
           using the meshless method of radial basis functions
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Mehdi Dehghan , Mohammad Shirzadi
      In this paper, we propose two numerical methods to solve the elliptic stochastic partial differential equations (SPDEs) in two and three dimensions obtained by Gaussian noises using radial basis functions (RBFs) collocation and pseudospectral (PS) collocation methods. For approximating the solution, generalized inverse multiquadrics (GIMQ) RBFs have been used. The Gaussian noises are approximated at the collocation points. The schemes work in a similar fashion as Hermite-based interpolation methods. The methods are tested via several problems. The numerical results show usefulness and accuracy of the new methods.


      PubDate: 2014-10-12T08:04:30Z
       
  • Extrapolated local radial basis function collocation method for shallow
           water problems
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): C.K. Chou , C.P. Sun , D.L. Young , J. Sladek , V. Sladek
      This paper provides a novel meshfree numerical method – the extrapolated local-radial-basis-function collocation method (ELRBFCM) – to solve the well-known shallow-water equations (or de Saint-Venant equations). To promote the accuracy and stability of the local-radial-basis-function collocation method (LRBFCM), the extrapolation method is employed in the ELRBFCM. The numerical experiments include the simulation of two linear and three non-linear problems. For the linear problems, the results of the extrapolation method not only have good agreement with analytical solutions, but also show better efficiency than the Euler and RK4 scheme. It is convinced that by the extrapolation process, the approximating order and stability of time integration is automatically controlled. For the non-linear problems, the solutions by the proposed method capture the physical reaction that also obtained in the benchmark by a complex high-order finite-volume method. As a result, it is concluded that even for very long period, the meshfree ELRBFCM with high-order temporal approximation can provide robust, high accurate and great efficient numerical simulation for the shallow-water problems.


      PubDate: 2014-10-08T06:36:07Z
       
  • Projection plane method for evaluation of arbitrary high order singular
           boundary integrals
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Xiao-Wei Gao , Wei-Zhe Feng , Kai Yang , Miao Cui
      In this paper, an efficient method for numerical evaluation of all kinds of singular curved boundary integrals from 2D/3D BEM analysis is proposed based on an operation technique on a projection line/plane. Firstly, geometry variables on a curved line/surface element are expressed in terms of parameters on the projection line/plane, and then all singularities are analytically removed by expressing the non-singular part of the integration kernel as a power series in a local distance defined on the projection line/plane. Also, a set of crucial relationships computing derivatives of intrinsic coordinates with respect to local orthogonal coordinates is derived. A few examples are provided to demonstrate the correctness and the stability of the proposed method.


      PubDate: 2014-10-08T06:36:07Z
       
  • Meshless local Petrov–Galerkin (MLPG) method for three-dimensional
           nonlinear wave equations via moving least squares approximation
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): E. Shivanian
      This paper proposes an approach based on the Galerkin weak form and moving least squares (MLS) approximation to simulate three space dimensional nonlinear wave equation of the form u tt + α u t + β u = u xx + u yy + u zz + δ g ( u ) u t + f ( x , y , z , t ) , 0 < x , y , z < 1 , t > 0 subject to given appropriate initial and Dirichlet boundary conditions. The main difficulty of methods in fully three-dimensional problems is the large computational costs. In the proposed method, which is a kind of Meshless local Petrov–Galerkin (MLPG) method, meshless Galerkin weak form is applied to the interior nodes while the meshless collocation method is used for the nodes on the boundary, so the Dirichlet boundary condition is imposed directly. In MLPG method, it does not require any background integration cells so that all integrations are carried out locally over small quadrature domains of regular shapes, such as circles or squares in two dimensions and spheres or cubes in three dimensions. The moving least squares approximation is proposed to construct shape functions. A two-step time discretization method is employed to approximate the time derivatives. To treat the nonlinearity, a kind of predictor–corrector scheme combined with one-step time discretization and Crank–Nicolson technique is adopted. Several numerical examples are presented and satisfactory agreements are achieved.


      PubDate: 2014-10-08T06:36:07Z
       
  • A Meshless Symplectic Algorithm for multi-variate Hamiltonian PDEs with
           Radial Basis Approximation
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Z. Wu , S. Zhang
      Based on radial basis approximation, in this paper we propose two methods to discretize the problem of multi-variate Hamiltonian system. One is discretizing the system and finding out the corresponding discrete Hamiltonian functional, which will be conserved with respect to the time. The other is discretizing the Hamiltonian functional and deriving the corresponding discrete Hamiltonian system. This helps open a new area of research in developing the expected meshless symplectic algorithm for multi-variate Hamiltonian systems with the scattered data points. Theoretical estimates including the truncation error and the global error are given. Numerical experiments verify the theoretical results. As numerical experiments show, the schemes are easy to implement with the scattered knots. Furthermore, the schemes possesss a long-time tracking capability for these Hamiltonian systems.


      PubDate: 2014-10-02T05:36:38Z
       
  • Generalized polyharmonic multiquadrics
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Chia-Cheng Tsai
      In this paper, we construct the two- and three-dimensional generalized polyharmonic multiquadrics (GPMQ) of order (K,L), which are the particular solution of the K-th order generalized multiquadrics (GMQ) associated with the L-th order polyharmonic operator for L>0. By observing the first few orders of the GPMQs, we construct methods of undetermined coefficients and determine the unknown coefficients by expanding the GPMQs into Laurent series. The derived GPMQs are hierarchically unique and infinitely differentiable. Then, the GPMQ definitions are extended for L<0 and the solutions are derived by similar methods. Both symbolic and floating-point implementations are performed for automatically obtaining the GPMQs of arbitrary orders, in which the former is explicitly provided and the later enables to implement numerical methods free from bookkeeping. The derived GPMQs are validated by numerical experiments, in which significant improvement on the accuracy can be observed.


      PubDate: 2014-10-02T05:36:38Z
       
  • Yield design of reinforced concrete slabs using a rotation-free meshfree
           method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Canh V. Le , Phuc L.H. Ho , Phuong H. Nguyen , Thang Q. Chu
      This paper presents a numerical kinematic procedure for yield design of reinforced concrete slabs governed by Nielsen׳s yield criterion that uses a rotation-free meshfree method and second-order cone programming. A moving least squares approximation technique is employed to approximate the transverse displacement field without using rotational degrees of freedom. A curvature smoothing stabilization technique is applied, ensuring that the size of the resulting optimization problem is reduced significantly. The resulting optimization was solved using a highly efficient primal-dual interior point algorithm. Various reinforced concrete slab problems with arbitrary geometries and different boundary conditions were solved to illustrate the efficacy of the proposed numerical procedure.


      PubDate: 2014-10-02T05:36:38Z
       
  • Fast and data sparse time domain BEM for elastodynamics
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Bernhard Kager , Martin Schanz
      Wave propagation is of great interest for all fields of science and engineering. Particularly, for the case of semi-infinite and infinite domains, the Boundary Element Method is an appropriate numerical method for the simulation of such problems. The presented formulation establishes a data efficient and fast boundary element formulation for the 3-d elastodynamic problem. Approximations of the inherently present temporal convolution are computed via the Convolution Quadrature Method in a nonstandard manner. Contrary to utilizing Cauchy׳s integral formula, this paper establishes a ‘direct’ convolution weight evaluation. The application of a cubic spline interpolation on these analytic functions and an appropriate clustering strategy, finally, yield a fast and data efficient formulation that is validated with numerical examples.


      PubDate: 2014-10-02T05:36:38Z
       
  • New analytical expressions in radial integration BEM for solving heat
           conduction problems with variable coefficients
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Kai Yang , Hai-Feng Peng , Miao Cui , Xiao-Wei Gao
      In this paper, a new approach using analytical expressions in the radial integration boundary element method (RIBEM) is presented for solving three kinds of representative variable coefficient heat conduction problems. This approach can improve the computational efficiency considerably and can overcome the time-consuming deficiency of RIBEM in computing involved radial integrals. Also, because it can solve any kinds of variable coefficient heat conduction problems, this approach has a very wide applicability. The fourth-order spline RBF is employed to approximate the unknowns appearing in domain integrals arising from the varying heat conductivity. The radial integration method is utilized to convert domain integrals to the boundary, which results in a pure boundary discretization algorithm. Numerical examples are given to demonstrate the efficiency of the presented approach.


      PubDate: 2014-10-02T05:36:38Z
       
  • A hybrid FE–BE method for SAR estimate in voxel based human models
           undergoing MRI
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): Oriano Bottauscio , Mario Chiampi , Luca Zilberti
      The paper discusses the application of a hybrid Finite Element–Boundary Element technique to the electromagnetic dosimetric analysis of voxel based human models, with particular attention to the Magnetic Resonance Imaging appliances. A rational organization of the large amount of data involved by the voxel anatomy is presented to reduce the computational burden. The most suitable choice of the unknowns and the possible simplifying assumptions are also investigated. A hybrid Finite Element–Boundary Element approach is derived from the previous considerations, underlining the procedure for the system solution adopted when the whole algebraic matrix exceeds the RAM capabilities. The work is completed with some examples of applications.


      PubDate: 2014-09-25T04:20:15Z
       
  • Editorial Board
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49




      PubDate: 2014-09-25T04:20:15Z
       
  • Special issue on: Boundary elements and other reduction methods in
           bioelectromagnetics
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): Dragan Poljak



      PubDate: 2014-09-25T04:20:15Z
       
  • On the use of the boundary element analysis in bioelectromagnetics
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): Dragan Poljak , Damir Cavka , Hrvoje Dodig , Cristina Peratta , Andres Peratta
      The paper reviews a boundary element analysis of the human exposure to electrostatic, low frequency (LF) and high frequency (HF) electromagnetic fields. The formulation for the low frequency exposures is based on the quasi-static approximation and the related Laplace equation form of the continuity equation. The assessment of high frequency exposures is based on the Helmholtz equation. The solution of the governing equations is carried out using certain boundary element procedures. Some illustrated computational examples are related to the human head exposed to electrostatic field from video display units (VDUs), pregnant woman/foetus exposure to extremely low frequency (ELF) fields from power lines and the human eye exposed to high frequency (HF) electromagnetic radiation.


      PubDate: 2014-09-25T04:20:15Z
       
  • An adaptive node regeneration technique for the efficient solution of
           elasticity problems using MDLSM method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): S. Nikravesh Kazeroni , M.H. Afshar
      An efficient adaptive node regeneration method is proposed in this paper for solving elasticity problems using the mixed discrete least squares meshless (MDLSM) method. The method starts with a point-wise error estimation of the solution produced on an arbitrary initial configuration defined by the user using the MDLSM method. The point-wise error estimate is associated with the support domain of the nodal points and used to calculate the required nodal spacing at each support domain and subsequently generate new nodes at support domain level. A node-removing process is then used to remove some of the nodes created at the overlapping regions of the support domains. To improve the quality of the final configuration, a node-moving procedure based on interpolation of the errors on the original configuration is used to create the final nodal configuration. The proposed method is a single step refinement procedure and is capable of producing nodal configurations of desired accuracy for different problems. The proposed method is used to simulate three benchmark examples from the literature and the results are produced and compared with those of the conventional multi-stage node enrichment method. The results indicate the superior efficiency and effectiveness of the proposed method compared to the available methods.


      PubDate: 2014-09-25T04:20:15Z
       
  • High gradient magnetic particle separation in a channel with bifurcations
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): M. Zadravec , M. Hriberšek , P. Steinmann , J. Ravnik
      Micro particle separation from solid–liquid suspension under the influence of hydrodynamic and magnetic forces in a channel with bifurcation is studied numerically by applying the Boundary Element Method based fluid flow solver. The particle trajectories are computed using the Lagrangian particle tracking, where the forces on particles are computed based on the point particle representation. In the separator due to the bifurcation channel geometry the magnetic particles experience varying Kelvin force as they travel along the channel, although in the same direction the high gradient magnetic field does not change. In this way, the interplay of hydrodynamic and magnetic forces leads to changes in collection efficiency of the separator. A comparison with magnetic separation in the narrow channel design is done and recommendation for optimal choice of fluid flow rate and magnitude of external magnetic field is discussed.


      PubDate: 2014-09-25T04:20:15Z
       
  • Specific absorption rate (SAR) revisited for the ellipsoidal model of a
           human body
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): Francesco Lattarulo
      An unexplored procedure leading to a unified formulation of the average whole-body SAR, thus entirely covering the frequency spectrum of technical interest, is here described. The explanatory and referential example of an ellipsoid mimicking exposition of a standing man on a ground plane is adopted and an approximate closed form for the SAR is provided. In spite of the far-field condition which in principle applies to this investigation, the analysis starts from rigorously recognizing the near-field performances of the time average Poynting vector and goes on accordingly in modeling the induction mechanism. Therefore, the external dosimetry is preliminary assessed by using a quasistatic approach. This step is rather to be intended as an intermediate one with the aim of evaluating the SAR which, as a consequence, results subject to the same quasistatic conditions. Indeed, the approximation error affecting the calculation especially depends on the fact that the adopted biological model behaves as a perfect conductor externally to its boundary and internally as a dissipating dielectric body. On the whole, the continuous curves obtained in function of frequency are in fairly good agreement with available counterparts which, do not forget, are rather constructed by interpolation of discontinuous databases given using different models and spanning restricted frequency ranges. The only striking departure consists in the smoothed appearance of the curves related to this method against the presence of a resonance sharp peak arising elsewhere under specialized exposure conditions. In the light of this theory, the peak in question is hard to explain, except when the adopted corpulent ellipsoid is replaced with a more refined model.


      PubDate: 2014-09-25T04:20:15Z
       
  • Simulation of laminar backward facing step flow under magnetic field with
           explicit local radial basis function collocation method
    • Abstract: Publication date: December 2014
      Source:Engineering Analysis with Boundary Elements, Volume 49
      Author(s): K. Mramor , R. Vertnik , B. Šarler
      The purpose of the present paper is to extend the use of a novel meshless Local Radial Basis Function Collocation Method (LRBFCM) for solving the two-dimensional, steady, laminar flow over a backward facing step under the influence of the Lorentz force. The incompressible Navier–Stokes equations are under the influence of predetermined static magnetic field numerically solved on a non-uniform node arrangement. In the numerical procedure, local collocation and Multiquadric Radial Basis Functions (MQ RBF) are used on five-nodded subdomains. The coupling between the pressure and the velocity is made by using Fractional Step Method (FSM). The considered problem is calculated for Reynolds numbers (Re) ranging from 300 to 800, Hartman numbers (Ha) ranging from 0 to 100, and for low magnetic Re m number. The numerical results demonstrate excellent agreement with previously published data, obtained with the classical numerical methods, such as Finite Volume Method (FVM) and Finite Element Method (FEM). Simplicity of the numerical implementation, accuracy and the absence of the polygonalisation are the main advantages of the LRBFCM.


      PubDate: 2014-09-25T04:20:15Z
       
  • The ACA–BEM approach with a binary-key mosaic partitioning for
           modelling multiple bubble dynamics
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Zhiwei Fu , Viktor Popov
      The fast algorithm adaptive cross approximation (ACA) is applied to accelerate the solution of the boundary element method (BEM). A new method for mosaic partitioning is proposed as part of the implementation of the ACA algorithm. It is based on a binary key system, which represents a hierarchical cluster tree and helps to identify the hierarchy within the ℋ -matrix generated by the BEM. The employed ACA approach proves efficient even for relatively small problems with the degree of freedom of O(103). As the problem size grows, the superior performance of the fast approach becomes more notable by comparison with that of the conventional boundary element method (CBEM). Modelling of bubble dynamics belongs to the moving boundary problems and can be efficiently analysed by using the BEM. By applying the ACA approach, the dense matrices via the collocation scheme are successfully compressed, and the developed model is capable of investigating the time-dependent evolution process of a relatively large number of bubbles (>100) in an efficient way.


      PubDate: 2014-09-21T03:35:17Z
       
  • Numerical solution of three-dimensional Laplacian problems using the
           multiple scale Trefftz method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Cheng-Yu Ku , Chung-Lun Kuo , Chia-Ming Fan , Chein-Shan Liu , Pai-Chen Guan
      This paper proposes the numerical solution of three-dimensional Laplacian problems based on the multiple scale Trefftz method with the incorporation of the dynamical Jacobian-inverse free method. A numerical solution for three-dimensional Laplacian problems was approximated by superpositioning T-complete functions formulated from 18 independent functions satisfying the governing equation in the cylindrical coordinate system. To mitigate a severely ill-conditioned system of linear equations, this study adopted the newly developed multiple scale Trefftz method and the dynamical Jacobian-inverse free method. Numerical solutions were conducted for problems involving three-dimensional groundwater flow problems enclosed by a cuboid-type domain, a peanut-type domain, a sphere domain, and a cylindrical domain. The results revealed that the proposed method can obtain accurate numerical solutions for three-dimensional Laplacian problems, yielding a superior convergence in numerical stability to that of the conventional Trefftz method.


      PubDate: 2014-09-21T03:35:17Z
       
  • An ultra-accurate hybrid smoothed finite element method for piezoelectric
           problem
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Eric Li , Z.C. He , L. Chen , Bing Li , Xu Xu , G.R. Liu
      An ultra-accurate hybrid smoothed finite element method (HS-FEM) is presented for the analysis of piezoelectric structures, in which the electrostatic equations governing piezoelectric problem are solved numerically with simplest triangular elements in 2D and tetrahedral elements in 3D. In the present method, the strain field is assumed to be the weighted average between compatible strains from finite element method (FEM) and smoothed strains from node-based smoothed finite element method (NS-FEM). Numerical results demonstrate that the proposed method possesses a novel bound solution in terms of strain energy and eigenfrequencies, which is very important for safety and reliability assessments of piezoelectric structural properties. In addition, the numerical results obtained from HS-FEM are much more accurate than the standard finite element method using the same of nodes. Furthermore, the computational efficiency of HS-FEM is much better than the FEM.


      PubDate: 2014-09-21T03:35:17Z
       
  • Free vibration analysis of stepped rectangular plates resting on
           non-homogeneous elastic foundations
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): M. Huang , T. Sakiyama , H. Matsuda , C. Morita
      A Half Boundary Method (HBM) is proposed for analyzing the free vibration problem of rectangular plates with stepped thickness resting on non-homogeneous elastic foundations. The unknown quantities of the method exist only on half of the boundary. The non-homogeneous elastic foundation discussed here consists of two-segment elastic Winkler foundation. The fundamental differential equations are established for the bending problem of the plate on elastic foundations. The Green function, which is obtained by transforming these differential equations into integral equations and using numerical integration, is used to establish the characteristic equation of the free vibration. The effects of the modulus of the foundation, the stepped thickness and aspect ratio on the frequency parameters are considered. By comparing the present numerical results with those previously published, the efficiency and accuracy of the present method are investigated.


      PubDate: 2014-09-21T03:35:17Z
       
  • Finding unknown heat source in a nonlinear Cauchy problem by the Lie-group
           differential algebraic equations method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Chein-Shan Liu
      We consider an inverse heat source problem of a nonlinear heat conduction equation, for recovering an unknown space-dependent heat source under the Cauchy type boundary conditions. With the aid of measured initial temperature and initial heat flux, which are disturbanced by random noise causing measurement error, we develop a Lie-group differential algebraic equations (LGDAE) method to solve the resultant differential algebraic equations. The Lie-group numerical method has a stabilizing effect to retain the solution on the associated manifold, which thus naturally has a regularization effect to overcome the ill-posed property of the nonlinear inverse heat source problem. As a consequence, we can quickly recover the unknown heat source under noisy input data only through a few iterations. The initial data used in the recovery of heat source are assumed to be the analytic continuation ones which are not given arbitrarily. Certainly, the measured initial data belong to this type data.


      PubDate: 2014-09-21T03:35:17Z
       
  • A Laplace transform DRBEM with a predictor–corrector scheme for
           
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Imam Solekhudin , Keng-Cheng Ang
      A problem involving time-dependent infiltration from periodic channels with root-water uptake is governed by Richards equation. To study the problem numerically, the governing equation is transformed into a modified Helmholtz equation using the Kirchhoff transformation, dimensionless variables, and Laplace transforms. The modified Helmholtz equation is then solved numerically using a dual reciprocity boundary element method (DRBEM) and a predictor–corrector scheme simultaneously. A numerical inverse Laplace transform is employed to obtain numerical solutions of the problem.


      PubDate: 2014-09-21T03:35:17Z
       
  • Application of complex SIE method for the prediction of hydrofracture path
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): A.A. Andreev , A.N. Galybin , O.Y. Izvekov
      This study is aimed at application of the method of complex singular integral equation (SIE) to the problem of crack propagation in non-uniform stress field. The paper examines one actual problem of oil and gas production: modeling of the hydrofracture trajectories in a reservoir subjected to non-uniform distributions of pore pressure. A modification of the method of mechanical quadratures is used to solve the SIE to simulate the hydro-fracture trajectory. The modification addresses discontinuities in the loads acting on the hydrofracture and provides quite accurate and fast solutions for the stress intensity factors. The crack path is modeled by a polygonal line such that the orientation of every subsequent leg is chosen by the criterion of maximum tensile stresses at the crack tip calculated for the current configuration. Different interposition the hydrofracture and the injection wells are examined.


      PubDate: 2014-09-21T03:35:17Z
       
  • Stochastic sensitivity of the electromagnetic distributions inside a human
           eye modeled with a 3D hybrid BEM/FEM edge element method
    • Abstract: Publication date: Available online 15 September 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): H. Dodig , S. Lalléchère , P. Bonnet , D. Poljak , K. El Khamlichi Drissi
      This contribution was dedicated to the assessment of the electromagnetic (EM) distributions inside a 3D modeled human eye. Since the use of accurate and efficient electromagnetic tools is crucial to obtain such results, an original hybrid boundary element method (BEM)/finite element method (FEM) is presented through the example of an EM wave impinging on the eye corneal region. Due to the variability inherent to the characterizing of living parameters (regarding our frequency range of interest about a few GHz), an accurate modeling of those mostly electrical data is necessary. A simple formalism based upon a “philosophy” close to Monte Carlo requirements is proposed in this paper in order to integrate efficiently and precisely uncertainties in the proposed results. The analysis of the sensitivity of different electrical parameters aims to increase a better knowledge of the EM fields distribution inside an eye. Obviously, both the deterministic EM modeling and the stochastic theoretical basis will be presented. The whole model will be illustrated on numerical examples including different random variables.


      PubDate: 2014-09-18T03:07:01Z
       
  • Multiobjective optimization for node adaptation in the analysis of
           composite plates using a meshless collocation method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): C.M.C. Roque , J.F.A. Madeira , A.J.M. Ferreira
      The bending of simply supported composite plates is analyzed using a direct collocation meshless numerical method. In order to optimize node distribution the Direct MultiSearch (DMS) for multiobjective optimization method is applied. In addition, the method optimizes the shape parameter in radial basis functions. The optimization algorithm was able to find good solutions for a large variety of nodes distribution.


      PubDate: 2014-09-18T03:07:01Z
       
  • Fully nonlinear wave interaction with freely floating non-wall-sided
           structures
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): B.Z. Zhou , G.X. Wu , B. Teng
      A fully nonlinear numerical model for a floating body in the open sea has been developed based on velocity potential together with a higher-order boundary element method (BEM). The total wave elevation and the total velocity potential are separated into two parts, based on the incoming wave from infinity and the disturbed potential by the body. The mesh is generated only once at the initial time and the element nodes are rearranged subsequently without changing their connectivity by using a spring analogy method. Through some auxiliary functions, the mutual dependence of fluid/structure motions are decoupled, which allows the body acceleration to be obtained without the knowledge of the pressure distribution. Numerical results are provided for forces and run-ups of a fixed cylinder with flare and the comparison is made with the second order theory in the frequency domain. Simulations are also made for a freely floating body responding to wave excitation. Resonance related to ringing excited by the high order force at the triple wave frequency is discussed. Further results are provided for motions, forces and run-ups of a floating cylinder with flare. Comparison with the results for the fixed body and body in single degree of freedom is made.


      PubDate: 2014-09-18T03:07:01Z
       
  • The general boundary element method for 3D dual-phase lag model of bioheat
           transfer
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Ewa Majchrzak , Lukasz Turchan
      Heat transfer processes proceeding in the 3D domain of heating tissue are discussed. The problem is described by dual-phase lag equation supplemented by adequate boundary and initial conditions. To solve the problem the general boundary element method is proposed. The examples of computations are presented in the final part of the paper. The efficiency and exactness of the algorithm proposed are discussed and the conclusions are also formulated.


      PubDate: 2014-09-10T01:48:39Z
       
  • Geometrically nonlinear elastodynamic analysis of hyper-elastic neo-Hooken
           FG cylinder subjected to shock loading using MLPG method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Mohammad Hossein Ghadiri Rad , Farzad Shahabian , Seyed Mahmoud Hosseini
      In this paper, geometrically nonlinear dynamic behavior of FG thick hollow cylinder under axisymmetric mechanical shock loading is investigated using meshless local Petrov–Galerkin (MLPG) method. The FG cylinder is assumed to be made of large deformable materials such as carbon-based polymers. Thus, the neo-Hooken hyper-elastic constitutive model is employed for the problem. The material properties of FG cylinder are varied as nonlinear function of radius in volume fraction forms. Radial point interpolation method is used to approximate the field variables in the local integral equations. Weak formulation on local sub-domains using a Heaviside test function is adopted to get the system of equations. It should be emphasized that the formulations are derived using total Lagrangian approach, which refers all variables to the initial configuration. The iterative Newmark/Newton–Raphson technique is used to solve the equilibrium equations. In order to verify the feasibility and accuracy of the presented method, a thick hollow FG cylinder is linearly analyzed and compared with published data. The dynamic behaviors of displacements and stresses are obtained using nonlinear analysis and discussed in details for various kinds of neo-Hooken FGMs.


      PubDate: 2014-09-10T01:48:39Z
       
  • Direct use of radial basis interpolation functions for modelling source
           terms with the boundary element method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Carlos F. Loeffler , Átila L. Cruz , André Bulcão
      In this paper a new technique is presented for transforming the domain integral related to the source term that characterizes the Poisson Equation, within the scope of the boundary element method, for two-dimensional problems. Similarly to the Dual Reciprocity Technique, the proposed scheme avoids domain discretization using primitive radial basis functions; however, it transforms the domain integral into a single boundary integral directly. The proposed procedure is simpler, more versatile and some useful and modern techniques related to radial basis function theory can be applied. Numerical tests show the accuracy of the proposed technique for a simple class of complete radial interpolation functions, pointing out the importance of internal poles and the potential of applying fitting interpolation schemes to minimize the computational storage, particularly considering more complex future approaches, in which a mass matrix may be generated. For the analysis of the accuracy and convergence of the proposed method, results are compared with those obtained using Dual Reciprocity, using known analytical solutions for reference.


      PubDate: 2014-09-10T01:48:39Z
       
  • Simulation of semiconductor devices with a local numerical approach
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): G. Kosec , R. Trobec
      A numerical solution of the Drift-Diffusion Model for simulation of semiconductor devices based on the local meshless numerical method is presented. Numerical difficulties inherited from convection-dominated processes and high gradients near junctions typically results in oscillations within the solution. The difficulties can be alleviated by artificial dissipation schemes or by other stabilization approaches that often require a complex computation to improve the solution convergence. We applied a simple numerical approach with a local coupling and without special treatments of nonlinearities. The proposed approach is straightforward to implement and is suitable for parallel execution. We demonstrate the efficiency of the proposed methodology on a simulation of PN junction. The results are compared against previously published data with a good agreement achieved. The applicability of the proposed methodology is confirmed with the simulation of extended tests with more complicated geometries and more intense dynamics. The computational efficiency is demonstrated through the measurement of execution time and speedup on shared memory computer architecture.


      PubDate: 2014-09-10T01:48:39Z
       
  • Editorial Board
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48




      PubDate: 2014-09-05T00:42:39Z
       
  • A least squares based meshfree technique for the numerical solution of the
           flow of viscoelastic fluids: A node enrichment strategy
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Mohsen Lashkarbolok , Ebrahim Jabbari , Jerry Westerweel
      A fully implicit least-squares-based meshfree method is used to solve the governing equations of viscoelastic fluid flow. Here, pressure is connected to the continuity equation by an artificial compressibility technique. A radial point interpolation method is used to construct the meshfree shape functions. The method is used to solve two benchmark problems. Thanks to the flexibility of meshfree methods in domain discretization, a simple node enrichment strategy is used to discrete the problem domain more purposefully. It is shown that the introduced enrichment process have a positive effect on the accuracy of the results.


      PubDate: 2014-09-05T00:42:39Z
       
  • Stress distribution of mine roof with the boundary element method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): R. Wu , J.H. Xu , C. Li , Z.L. Wang , S. Qin
      Mine roof, is a stiff rock strata, located on the top of coal seam, which can prevent the deformation and control the stability of coal roadway after the coal roadway is tunneled, so mine roof is one of the most important structures in coal mining engineering. In this paper, mine roof is treated as elastic plate, which is studied thoroughly at the theoretical level. Based on the mechanical models of plane and stress analysis for elastic roof, using the boundary integral equation which is obtained by the natural boundary reduction, this paper obtains stress functions of elastic half roof, as well as the analytical and numerical solutions to the each stress field functions. We also analyze the rules of different stress distributions for roof under a concentrated force and a uniform distribution load, the results of calculation show uniformity of the stress distribution. In order to research the mine roof deformation law, Mohr–Coulomb model is established to describe the deformation behavior of roof surrounding rock, FLAC3D is also used to simulate the deformation of roof after the coal roadway is tunneled under different length of coal roadway excavation. The comparison result between BEM solution and FLAC3D simulation shows advantages to solve the problem by boundary element method, and numerical simulation proves the deformation behavior of roof is influenced by the length of coal roadway excavation.


      PubDate: 2014-09-05T00:42:39Z
       
  • A fast directional BEM for large-scale acoustic problems based on the
           Burton–Miller formulation
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Yanchuang Cao , Lihua Wen , Jinyou Xiao , Yijun Liu
      In this paper, a highly efficient fast boundary element method (BEM) for solving large-scale engineering acoustic problems in a broad frequency range is developed and implemented. The acoustic problems are modeled by the Burton–Miller boundary integral equation (BIE), thus the fictitious frequency issue is completely avoided. The BIE is discretized by using the Nyström method based on the curved quadratic elements, leading to simple numerical implementation (no edge or corner problems) and high accuracy in the BEM analysis. The linear systems are solved iteratively and accelerated by using a newly developed kernel-independent wideband fast directional algorithm (FDA) for fast summation of oscillatory kernels. In addition, the computational efficiency of the FDA is further promoted by exploiting the low-rank features of the translation matrices, resulting in two- to three-fold reduction in the computational time of the multipole-to-local translations. The high accuracy and nearly linear computational complexity of the present method are clearly demonstrated by typical examples. An acoustic scattering problem with dimensionless wave number kD (where k is the wave number and D is the typical length of the obstacle) up to 1000 and the degrees of freedom up to 4 million is successfully solved within 10h on a computer with one core and the memory usage is 24GB.


      PubDate: 2014-09-05T00:42:39Z
       
  • A modified scaled boundary approach in frequency domain with diagonal
           coefficient matrices
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Masoud Hajialilue-Bonab , Hamid Reza Tohidvand
      In order to solve the scaled boundary differential equation in dynamic stiffness, an initial value is needed. This initial value can be obtained using high frequency asymptotic expansion of dynamic stiffness matrix. Expanded dynamic stiffness matrix of unbounded mediums at high frequency was presented by previous researchers based on the fully populated coefficient matrices. In this paper, lumped coefficient matrices are used to modify the scaled boundary procedure. Some extra computational efforts of the original scaled boundary method can be eliminated using the proposed approach. The scaled boundary spectral element method (SBSEM) is used to achieve lumped coefficient matrices. It is shown that the proposed method leads to correct dynamic stiffness matrix. Therefore, it can be applied to solve scaled boundary differential equation of unbounded mediums, efficiently. A comparison between the results of the modified and the original methods is presented and accuracy of the modified method is investigated.


      PubDate: 2014-08-14T23:16:10Z
       
  • PROMETHEE technique to select the best radial basis functions for solving
           the 2-dimensional heat equations based on Hermite interpolation
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Saeed Kazem , Farhad Hadinejad
      In this work, we have decided to select the best radial basis functions for solving the 2-dimensional heat equations by applying the multiple criteria decision making (MCDM) techniques. Radial basis functions (RBFs) based on the Hermite interpolation have been utilized to approximate the solution of heat equation by using the collocation method. Seven RBFs, Gaussian (GA), Multiquadrics (MQ), Inverse multiquadrics (IMQ), Inverse quadrics (IQ), third power of Multiquadrics (MQ3), Conical splines (CS) and Thin plate Splines (TPS), have been applied as basis functions as well. In addition, by choosing these functions as alternatives and calculating the error, condition number of interpolation matrix, RAM memory and CPU time, obtained by Maple software, as criteria, rating of cases with the help of PROMETHEE technique has been investigated. In the end, the best function has been selected according to the rankings.


      PubDate: 2014-08-14T23:16:10Z
       
  • On the use of the vertical straight wire model in electromagnetics and
           related boundary element solution
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Dragan Poljak , Silvestar Šesnić , Damir Cavka , Khalil El Khamlichi Drissi
      The paper deals with an analysis of various EMC problems related to radiation and scattering from wires using a vertical straight wire model based on the corresponding Pocklington integro-differential equation. The rigorous solution of the Pocklington type equation is undertaken via the Galerkin–Bubnov Indirect Boundary Element Method (GB-IBEM). Many illustrative computational examples presented throughout the paper are related to dipole antenna above a lossy half-space, metal rods penetrating the ground, lightning channel and vertical grounding electrode. Obtained numerical results are somewhere compared to NEC or analytical results, respectively.


      PubDate: 2014-08-14T23:16:10Z
       
  • A numerical study of Asian option with radial basis functions based finite
           differences method
    • Abstract: Publication date: January 2015
      Source:Engineering Analysis with Boundary Elements, Volume 50
      Author(s): Alpesh Kumar , Lok Pati Tripathi , Mohan K. Kadalbajoo
      The purpose of this paper is to design and describe the valuation of Asian option by radial basis function approximation. A one state variable partial differential equation which characterizes the price of European type Asian option is discussed. The governing equation is discretized by the θ-method and the option price is approximated by radial basis function based finite difference method. Numerical experiments are performed with European option and Asian option and results are compared with theoretical and numerical results available in the literature. We show numerically that the scheme is second order accurate. Stability of the scheme is also discussed.


      PubDate: 2014-08-14T23:16:10Z
       
  • An explicit time integration scheme of numerical manifold method
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): X.L. Qu , G.Y. Fu , G.W. Ma
      The traditional numerical manifold method (NMM) has the advantage of simulating a continuum and a discontinuum in a unified framework based on a dual cover system. However, since an implicit time integration algorithm is used, the computational efficiency of the original NMM is very low, especially when more contacts are involved. The present study proposes an explicit version of the NMM. Since a lumped mass matrix is used for the manifold element, the accelerations by the corresponding physical covers can be solved explicitly without forming a global stiffness matrix. The open–close iteration is still applied to ensure computational accuracy. The developed method is first validated by two examples, and a highly fractured rock slope is subsequently simulated. Results show that the computational efficiency of the proposed explicit NMM has been significantly improved without losing the accuracy. The explicit NMM is more suitable for large-scale rock mass stability analysis and it deserves to be further developed for engineering computations in rock engineering.


      PubDate: 2014-08-10T23:03:20Z
       
  • A three-dimensional crack growth simulator with displacement discontinuity
           method
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Jingyu Shi , Baotang Shen , Ove Stephansson , Mikael Rinne
      This paper first outlines the theory of a well established three dimensional boundary element method: displacement discontinuity method (DDM) and proposes to use a crack growth criterion based on maximum normal or shear stress for a three dimensional crack growth simulator, FRACOD3D. Triangular elements are used in the simulator code. A numerical scheme is used to overcome a difficulty associated with the evaluation of the basic solution for DDM in some special situations and another numerical scheme is used to calculate the stresses on the boundary elements where the stresses obtained from the normal DDM scheme have large errors. The crack growth is implemented incrementally in that new front elements are introduced at the crack front; thus no need to re-mesh the old part of the cracks. The effects of neighbouring front elements are taken into account in implementation of the crack growth to overcome severer twisting of the new front elements generated from the growth. The numerical results from FRACOD3D of two simple examples agree very well with analytical solutions, and propagation configuration of a circular disc crack in an infinite body under shear is close to that observed in an experiment in literature under similar loading condition.


      PubDate: 2014-08-10T23:03:20Z
       
  • Approximation schemes of stresses on elements for the three-dimensional
           displacement discontinuity method
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Jingyu Shi , Baotang Shen
      The displacement discontinuity method is a boundary element method. It uses the analytical expressions for displacements and stresses in an infinite isotropic homogeneous linear elastic body caused by difference (discontinuity) of displacements across small planar crack surfaces. The basic solution of the method is the displacement discontinuities (DDs) across the crack elements. After DDs are obtained, the displacement and stresses at other points in the body can be calculated. It discretises the crack without considering the individual surface of the crack, thus for crack propagation issues, it uses fewer (half) number of elements than normal BEM and therefore less computation time and computer memory requirement. However, it is found that the stresses calculated from the DDs for points on and close to the crack have large errors. Here we present two numerical schemes for approximation of stresses on the crack elements in three-dimensional problems, which are implemented in a code for fracture propagation. The schemes give a reasonably accurate approximation for elements where the crack surface is relatively smooth. It is found that for elements next to sharp kinking or at the corner of a crack, the results from the schemes are not satisfactory. A modification is proposed for these cases.


      PubDate: 2014-08-10T23:03:20Z
       
  • Computation of nearly singular integrals in 3D BEM
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Yaoming Zhang , Xiaochao Li , Vladimir Sladek , Jan Sladek , Xiaowei Gao
      This paper presents a general methodology for numerical evaluation of the nearly singular 2D integrals over the eight-node second-order quadrilateral geometry elements arising in 3D BEM. An accurate formula of distance between the source and the field point is proposed firstly. And then an extended form of the exponential transformation, which was firstly proposed by present author to regularize nearly singular integrals arising in 2D BEM, is developed to smooth out the rapid variation of the aforementioned formula of distance. Finally, several numerical examples involving boundary layer effect and thin body problems in 3D elastostatics are investigated to verify the proposed scheme, yielding very promising results. Moreover, it should be stressed that the proposed scheme is suitable for any high-order surface elements.


      PubDate: 2014-08-10T23:03:20Z
       
  • Groundwater flow simulation in unconfined aquifers using meshless local
           Petrov–Galerkin method
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Boddula Swathi , T.I. Eldho
      The complex behaviour of the aquifer system is generally studied by solving a set of governing equations using either analytical or numerical methods. Numerical techniques like finite difference method (FDM) and finite element method (FEM) are generally being used to solve such problems, as analytical solutions can be obtained only for simple cases. The Meshless methods are the recently developed numerical technique which can be alternatively used for solving the groundwater problem. A variety of Meshless methods are under intense research for the development of solution for many engineering problems. As no meshing, it can save substantial cost and time on pre-processing, unlike mesh based methods, which require meshing and re-meshing. In this paper, the Galerkin equivalent of Meshless Local Petrov–Galerkin (MLPG) method with Exponential/Gaussian Radial basis function (EXP–RBF) is used for the first time for solving the unconfined groundwater problem. Computer models in MATLAB have been developed in 2D for the solution of unconfined aquifer problems. The developed models are verified with available analytical and numerical solutions. The results are found to be satisfactory. The present study shows that the MLPG based method can be used in the effective simulation of groundwater flow problems.


      PubDate: 2014-08-10T23:03:20Z
       
  • Upwind strategies for local RBF scheme to solve convection dominated
           problems
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Y.V.S.S. Sanyasiraju , Chirala Satyanarayana
      The most common strategy existing in the literature for solving convection dominated Convection–Diffusion Equations (CDE) is using central approximation to the diffusive terms and upwind approximation to the convective terms. In the present work, we propose a multiquadric local RBF based grid-free upwind (LRBF_U) scheme for solving convection dominated CDE. In this method, the entire CDE operator is discretized over the nodes in the upwind local support domain for strongly convection dominant problems. The variable (optimal) shape parameter for LRBF_U scheme has been obtained by using a local optimization algorithm developed by the authors. It has been observed that for highly convection dominated problems, the LRBF_U scheme produces stable and accurate results. The proposed scheme is also been compared with the conventional Central-Upwind combined scheme, to demonstrate its superiority in generating high accurate solutions than the latter.


      PubDate: 2014-07-27T22:15:52Z
       
  • The mystery of the shape parameter IV
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): Lin-Tian Luh
      This is the fourth paper of our study of the shape parameter c contained in the famous multiquadrics ( − 1 ) ⌈ β ⌉ ( c 2 + ‖ x ‖ 2 ) β , β > 0 , and the inverse multiquadrics ( c 2 + ‖ x ‖ 2 ) β , β < 0 . The theoretical ground is the same as the third paper. However, we extend the space of interpolated functions to a more general one. This leads to a totally different set of criteria of choosing c.


      PubDate: 2014-07-27T22:15:52Z
       
  • An efficient transient analysis of realistic grounding systems:
           Transmission line versus antenna theory approach
    • Abstract: Publication date: November 2014
      Source:Engineering Analysis with Boundary Elements, Volume 48
      Author(s): B. Nekhoul , D. Poljak , D. Sekki , D. Cavka , B. Harrat , K. Kerroum , K. El Khamlichi Drissi
      An efficient transmission line (TL) model for the analysis of the transient behavior of realistic grounding system is presented. The model is based on the general solution of the TL equations in the frequency domain expressed in terms of the Φ-matrix, or the direct time domain solution based on the Finite Difference Time Domain (FDTD) method. The presented TL approach provides relatively simple numerical implementation, accurate results and requires rather low computational time. The accuracy of the results obtained via TL approach is in a good agreement with the numerical results computed via the rigorous antenna theory approach based on the integral equation formulation and corresponding boundary element solution.


      PubDate: 2014-07-27T22:15:52Z
       
 
 
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