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  Subjects -> ENGINEERING (Total: 1963 journals)
    - CHEMICAL ENGINEERING (151 journals)
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    - ENGINEERING (1120 journals)
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ENGINEERING (1120 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  
Diálogos Interdisciplinares     Open Access  
Diamond Light Source Proceedings     Full-text available via subscription  
Digital Signal Processing     Hybrid Journal   (Followers: 4)
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: 14)
Energies     Open Access   (Followers: 1)
Energy and Power Engineering     Open Access   (Followers: 6)
Energy Conversion and Management     Hybrid Journal   (Followers: 6)
Energy Engineering     Full-text available via subscription   (Followers: 8)
Energy for Sustainable Development     Hybrid Journal   (Followers: 8)
Energy Procedia     Open Access   (Followers: 2)
Energy Science & Engineering     Open Access   (Followers: 3)
Energy Science and Technology     Open Access   (Followers: 9)
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: 8)
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: 15)
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: 3)
Engineering Education     Open Access  
Engineering Failure Analysis     Hybrid Journal   (Followers: 22)
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: 5)
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  
Ergonomics in Design: The Quarterly of Human Factors Applications     Hybrid Journal   (Followers: 5)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription  
ESAIM: Mathematical Modelling and Numerical Analysis     Full-text available via subscription   (Followers: 3)
ESAIM: Proceedings     Open Access  
Estuaries and Coasts     Hybrid Journal   (Followers: 3)
EURASIP Journal on Advances in Signal Processing     Open Access   (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: 9)
Evolutionary Intelligence     Hybrid Journal  
Evolving Systems     Hybrid Journal  
Exacta     Open Access  
Experimental Techniques     Hybrid Journal   (Followers: 15)
Experiments in Fluids     Hybrid Journal   (Followers: 5)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Filtration & Separation     Full-text available via subscription   (Followers: 1)
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 2)
Fire Science Reviews     Open Access   (Followers: 1)
First Monday     Open Access   (Followers: 147)
Flexible Services and Manufacturing Journal     Hybrid Journal   (Followers: 2)
Flow, Turbulence and Combustion     Hybrid Journal   (Followers: 14)
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)
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: 5)
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
Foundations of Science     Hybrid Journal  
Frontiers in Aerospace Engineering     Open Access   (Followers: 3)
Frontiers in Energy     Hybrid Journal   (Followers: 2)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover Engineering Analysis with Boundary Elements
   [3 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0955-7997
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.22]   [H-I: 39]
  • An improved boundary distributed source method for electrical resistance
           tomography forward problem
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Sin Kim , Rong Li Wang , Anil Kumar Khambampati , Bo An Lee , Kyung Youn Kim
      This paper presents a meshless method called the improved boundary distributed source (IBDS) method to obtain the numerical solution of an electrical resistance tomography (ERT) forward problem. The ERT forward problem contains solving the Laplace equation on piece-wise homogeneous domain subjected to the mixed boundary conditions with constraints of integral form. The IBDS method is mesh-free and does not require a fictitious boundary for source points as in the case of a conventional method of fundamental solution (MFS) approach. Therefore, it can be used for a wide variety of applications involving complex shaped objects that are difficult to mesh. Also, in the IBDS method, the diagonal elements for Neumann boundary conditions are computed analytically unlike the original BDS method. Therefore, the IBDS method is computationally efficient and stable compared to the BDS method. The ERT forward problem to compute the boundary voltages is formulated using a meshless IBDS method. Several numerical examples are tested to demonstrate the feasibility and accuracy of the new formulation. The results are compared with that of standard numerical forward solvers for ERT such as the boundary element method (BEM) and the finite element method (FEM).


      PubDate: 2014-06-14T16:33:59Z
       
  • The singular boundary method: Mathematical background and application in
           orthotropic elastic problems
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Yan Gu , Wen Chen , Zhuo-Jia Fu , Bo Zhang
      The singular boundary method (SBM) is a recent strong-form boundary discretization numerical technique and can be viewed as one kind of modified method of fundamental solutions (MFSs). Although the method has been successfully used in many fields of engineering analysis, there has been no attempt yet to present a work discussing the mathematical background of the method. This paper fills this gap in the SBM and documents the first attempt to apply the method to the solution of orthotropic elastic problems. Three benchmark numerical problems are tested to demonstrate the feasibility and accuracy of the proposed method through detailed comparisons with the MFS and the boundary element method (BEM).


      PubDate: 2014-06-14T16:33:59Z
       
  • Coupled BEM–MLPG acoustic analysis for non-homogeneous media
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): A. Tadeu , P. Stanak , J. Sladek , V. Sladek
      A technique that couples the boundary element method (BEM) with the meshless local Petrov–Galerkin (MLPG) method is proposed to simulate the 2-D acoustic wave propagation in an unbounded fluid domain containing confined subdomains where the material properties vary from point to point. The non-homogeneous confined subdomains are only discretized with nodal points and treated by the MLPG. The nodal points, which are placed at the interface between the confined subdomains and the unbounded homogenous acoustic fluid, are used to couple the BEM and the MPLG. The moving least-squares (MLS) approximation scheme is used to provide the approximation of field quantities. The proposed BEM–MLPG coupled approach is verified against the results provided by an analytical solution developed for a circular confined subdomain, in which the velocity variation within the circular non-homogeneous region only occurs in the radial direction. A numerical example illustrates the application of the proposed approach to solve the case of a pair of non-homogeneous confined subdomains, for which analytical solutions are not known.


      PubDate: 2014-06-14T16:33:59Z
       
  • Natural convection heat transfer at high Rayleigh numbers – Extended
           meshless local Petrov–Galerkin (MLPG) primitive variable method
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Mohammad Najafi , Vali Enjilela
      The meshless local Petrov–Galerkin (MLPG) method is extended using an improved primitive variable formulation to solve the two-dimensional laminar natural convection equations. The extended method solves the natural convection heat transfer problems at high Rayleigh numbers. The method uses the fractional step scheme for discretization, and the moving least square (MLS) interpolation for approximation of the field variables. For the proposed technique, a weighting function of unity is used. The improved method considers the natural convection in a square cavity for up to and including Ra = 10 8 , in a concentric square outer cylinder and circular inner cylinder annulus for up to and including Ra = 10 7 , and in a two concentric circular cylinders annulus for up to and including Ra = 10 5 . Comparing the results of the three test cases obtained using the present method with those obtained using the conventional methods shows very good agreement existing among the appropriate results, hence, verifying the proposed improved meshless numerical technique.


      PubDate: 2014-06-14T16:33:59Z
       
  • Editorial Board
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43




      PubDate: 2014-06-14T16:33:59Z
       
  • A regularized multi-level technique for solving potential problems by the
           method of fundamental solutions
    • Abstract: Publication date: Available online 6 June 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): Csaba Gáspár
      The method of fundamental solutions is investigated in the case when the source points are located along the boundary of the domain of the original problem and coincide with the collocation points. The appearing singularities are eliminated by several techniques: by using approximate but continuous fundamental solutions (regularization) and via auxiliary subproblems to avoid the stronger singularities that appear in the normal derivatives of the fundamental solution (desingularization). Both monopole and dipole formulations are investigated. A special iterative solution algorithm is presented, which converts the original (mixed) problem to a sequence of pure Dirichlet and pure Neumann subproblems. The pure subproblems can be handled efficiently by using conjugate gradients. The efficiency is significantly increased by embedding the resulting method in a natural multi-level context. At the same time, the problem of the use of highly ill-conditioned matrices is also avoided.


      PubDate: 2014-06-14T16:33:59Z
       
  • BEM analysis of laterally loaded pile groups in multi-layered transversely
           isotropic soils
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Zhi Yong Ai , Dong Liang Feng
      Based on an analytical layer-element solution of multi-layered transversely isotropic soils, a boundary element method is adopted to analyze laterally loaded fixed-head pile groups. The pile–soil–pile interaction is considered directly by coupling the global stiffness matrix of pile groups and the soil׳s global flexibility matrix at the pile–soil interface. Good and reasonable agreement is obtained between the proposed and published solutions. A typical numerical example is presented to study the behavior of laterally loaded pile groups embedded in multi-layered transversely isotropic soils.


      PubDate: 2014-06-14T16:33:59Z
       
  • Singular boundary method for modified Helmholtz equations
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Wen Chen , Jin-Yang Zhang , Zhuo-Jia Fu
      This study makes the first attempt to apply a recent strong-form boundary collocation method using the singular fundamental solutions, namely the singular boundary method (SBM), to 2D and 3D modified Helmholtz equations. By the desingularization of subtracting and adding-back technique, the corresponding nonsingular SBM formulations are derived based on null-field integral equations and an inverse interpolation technique. Numerical demonstrations show the feasibility and accuracy of the present SBM in some benchmark problems.


      PubDate: 2014-06-14T16:33:59Z
       
  • Proof of linear independence of flat-top PU-based high-order approximation
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): X.M. An , X.Y. Liu , Z.Y. Zhao , L. He
      This paper extends a rank deficiency counting approach, which was initially established by An et al. (2011, 2012 [1,2]) to determine the rank deficiency of finite element partition of unity (PU)-based approximations, to explicitly prove the linear independence of the flat-top PU-based high-order polynomial approximation. The study also examines the coupled flat-top PU and finite element PU-based approximation, and the results indicate that the space at a global level is also linearly independent for 1-D setting and 2-D setting with triangular mesh, but not so for rectangular mesh. Moreover, a new procedure is proposed to simplify the construction of flat-top PU, and its feasibility, accuracy and efficiency have been validated by a typical numerical example.


      PubDate: 2014-06-14T16:33:59Z
       
  • Analytical expressions for evaluation of radial integrals in stress
           computation of functionally graded material problems using RIBEM
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Kai Yang , Yun-Fei Liu , Xiao-Wei Gao
      This paper presents a set of new analytical expressions for evaluating radial integrals appearing in the stress computation of variable coefficient elastic problems using the radial integration boundary element method (RIBEM). The strong singularity involved in the stress integral equation is explicitly removed in the derivation of the analytical expressions. The fourth-order spline RBF is employed to approximate unknowns appearing in domain integrals from variation of the shear modulus. Using these analytical expressions, considerable computational efficiency can be improved by overcoming the time-consuming deficiency of using the radial integration method (RIM) to convert domain integrals to the boundary which results in a pure boundary discretization algorithm in solving variable coefficient problems. Numerical examples are given to demonstrate the efficiency of the presented formulations.


      PubDate: 2014-06-14T16:33:59Z
       
  • Crack growth modeling in elastic solids by the extended meshfree Galerkin
           radial point interpolation method
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Nha Thanh Nguyen , Tinh Quoc Bui , Chuanzeng Zhang , Thien Tich Truong
      We present a new approach based on local partition of unity extended meshfree Galerkin method for modeling quasi-static crack growth in two-dimensional (2D) elastic solids. The approach utilizing the local partition of unity as a priori knowledge on the solutions of the boundary value problems that can be added into the approximation spaces of the numerical solutions. It thus allows for extending the standard basis functions by enriching the asymptotic near crack-tip fields to accurately capture the singularities at crack-tips, and using a jump step function for the displacement discontinuity along the crack-faces. The radial point interpolation method is used here for generating the shape functions. The representation of the crack topology is treated by the aid of the vector level set technique, which handles only the nodal data to describe the crack. We employ the domain-form of the interaction integral in conjunction with the asymptotic near crack-tip field to extract the fracture parameters, while crack growth is controlled by utilizing the maximum circumferential stress criterion for the determination of its propagating direction. The proposed method is accurate and efficient in modeling crack growths, which is demonstrated by several numerical examples with mixed-mode crack propagation and complex configurations.


      PubDate: 2014-06-14T16:33:59Z
       
  • Optimal algorithms in a Krylov subspace for solving linear inverse
           problems by MFS
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Chein-Shan Liu
      The method of fundamental solutions (MFS) is used to solve backward heat conduction problem, inverse heat source problem, inverse Cauchy problem and inverse Robin problem. In order to overcome the ill-posedness of resulting linear equations, two optimal algorithms with optimal descent vectors that consist of m vectors in a Krylov subspace are developed, of which the m weighting parameters are determined by minimizing a properly defined merit function in terms of a quadratic quotient. The optimal algorithms OA1 and OA2 are convergent fast, accurate and robust against large noise, which are confirmed through numerical tests.


      PubDate: 2014-06-14T16:33:59Z
       
  • Regularized symmetric positive definite matrix factorizations for linear
           systems arising from RBF interpolation and differentiation
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Scott A. Sarra
      Scattered data interpolation using Radial Basis Functions involves solving an ill-conditioned symmetric positive definite (SPD) linear system (with appropriate selection of basis function) when the direct method is used to evaluate the problem. The standard algorithm for solving a SPD system is a Cholesky factorization. Severely ill-conditioned theoretically SPD matrices may not be numerically SPD (NSPD) in which case a Cholesky factorization fails. An alternative symmetric matrix factorization, the square root free Cholesky factorization, has the same flop count as a Cholesky factorization and is successful even when a matrix ceases to be NSPD. A regularization method can be used to prevent the failure of the Cholesky factorization and to improve the accuracy of both SPD matrix factorizations when the matrices are severely ill-conditioned. The specification of the regularization parameter is discussed as well as convergence/stopping criteria for the algorithm. The formation of differentiation matrices with the regularized SPD factorizations is demonstrated to improve eigenvalue stability properties of RBF methods for hyperbolic PDEs.


      PubDate: 2014-06-14T16:33:59Z
       
  • A fractional step local boundary integral element method for unsteady
           two-dimensional incompressible flow
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Karel Kovářík , Juraj Mužík , Dana Sitányiová
      A meshless local boundary integral method is used to analyse incompressible fluid flow in two-dimensional domains. The method solves the incompressible Navier–Stokes equations in terms of the primitive variables using the characteristic-based split scheme. The basic equations are derived via interpolation using radial basis functions. Three test cases are presented here: unsteady Couette flow and the problems of a lid-driven cavity and a backward-facing step. The procedure produces stable solutions with results comparable to those of other conventional methods.


      PubDate: 2014-06-14T16:33:59Z
       
  • Implementation of the numerical manifold method for thermo-mechanical
           fracture of planar solids
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): H.H. Zhang , G.W. Ma , F. Ren
      The numerical manifold method (NMM) is developed to solve thermo-mechanical fracture problems in two-dimensional setting. The temperature fields are firstly determined through steady heat conduction analysis and then imported into the mechanical simulation. The temperature and displacement discontinuities across crack faces are essentially captured due to the dual cover systems in the NMM. To account for the singularity of thermal flux and stresses at the crack tip, the associated asymptotic basis is adopted in the cover functions for thermal and mechanical computation, respectively. The stress intensity factors are calculated with the domain-independent interaction integral. The accuracy of the proposed method is tested through several numerical examples including single, double and multiple-branched cracks and the results agree well the available solutions from the literature. The superiority of the NMM in the multi-field discontinuity modeling is preliminarily verified through the present work.


      PubDate: 2014-06-14T16:33:59Z
       
  • The complex variable reproducing kernel particle method for
           two-dimensional inverse heat conduction problems
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Y.J. Weng , Z. Zhang , Y.M. Cheng
      The complex variable reproducing kernel particle method (CVRKPM) for two-dimensional inverse heat conduction problems is presented in this paper. In the CVRKPM, the shape function of a two-dimensional problem is formed with one-dimensional basis function, the Galerkin weak form is employed to obtain the discretized system equation, and the penalty method is used to apply the essential boundary conditions, then the corresponding formulae of the CVRKPM for two-dimensional inverse heat conduction problems are obtained. Numerical examples are given to show that the method in this paper has higher computational accuracy and efficiency compared with the conventional element-free Galerkin (EFG) method and the reproducing kernel particle method (RKPM).


      PubDate: 2014-06-14T16:33:59Z
       
  • Panel method for mixed configurations with finite thickness and zero
           thickness
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): José M. Ezquerro , Victoria Lapuerta , Ana Laverón-Simavilla , José M. García , Taisir Avilés
      Panel methods are well-known methods for solving potential fluid flow problems. However, mixed configurations of obstacles with finite thickness and zero thickness have not been solved with these methods. Such configurations arise naturally in delta wings, sailing boats, and even in complete aircraft aerodynamics. In this work, a new numerical approach is proposed for solving 2D mixed configurations of obstacles with finite thickness and zero thickness. The method is based on the Dirichlet and Neumann formulations and is checked by comparison with analytical results.


      PubDate: 2014-06-14T16:33:59Z
       
  • A domain renumbering algorithm for multi-domain boundary face method
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): Jianming Zhang , Chenjun Lu , Yuan Li , Lei Han , Pan Wang , Guangyao Li
      In this paper, a domain number optimization algorithm for the multi-domain boundary face method is proposed. The advantage of the algorithm is to make nonzero blocks of the overall assembled matrix are as close to the main diagonal as possible. This will minimize the block fill-in effect that occurs during the solution process. Consequently, the time used for LU-decomposition and the memory requirement of the matrix will be reduced significantly. In this algorithm, one or more level structures are generated by considering the freedom degrees and the connectivity of the domains. Then we renumber the domains according to the level structure of the smallest bandwidth. Four steady-state heat conduction problems of multi-domain are solved to test the algorithm, and high efficiency is observed.


      PubDate: 2014-06-14T16:33:59Z
       
  • Simulation of plant cell shrinkage during drying – A SPH–DEM
           approach
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44
      Author(s): H.C.P. Karunasena , W. Senadeera , R.J. Brown , Y.T. Gu
      Plant based dried food products are popular commodities in global market where much research is focused to improve the products and processing techniques. In this regard, numerical modeling is highly applicable and in this work, a coupled meshfree particle-based two-dimensional (2-D) model was developed to simulate microscale deformations of plant cells during drying. Smoothed Particle Hydrodynamics (SPH) was used to model the viscous cell protoplasm (cell fluid) by approximating it to an incompressible Newtonian fluid. The visco-elastic characteristic of the cell wall was approximated to a Neo-Hookean solid material augmented with a viscous term and modeled with a Discrete Element Method (DEM). Compared to a previous work [44], this study proposes three model improvements: linearly decreasing positive cell turgor pressure during drying, cell wall contraction forces and cell wall drying. The improvements made the model more comparable with experimental findings on dried cell morphology and geometric properties such as cell area, diameter, perimeter, roundness, elongation and compactness. This single cell model could be used as a building block for advanced tissue models which are highly applicable for product and process optimizations in Food Engineering.


      PubDate: 2014-06-14T16:33:59Z
       
  • Editorial Board
    • Abstract: Publication date: July 2014
      Source:Engineering Analysis with Boundary Elements, Volume 44




      PubDate: 2014-06-14T16:33:59Z
       
  • Non-singular Method of Fundamental Solutions for anisotropic elasticity
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): Q.G. Liu , B. Šarler
      The purpose of the present paper is to develop a Non-singular Method of Fundamental Solutions (NMFS) for two-dimensional anisotropic linear elasticity problems. The NMFS is based on the classical Method of Fundamental Solutions (MFS) with regularization of the singularities. This is achieved by replacing the concentrated point sources with distributed sources over disks around the singularity, as recently developed for isotropic elasticity problem. In case of the displacement boundary conditions, the values of distributed sources are calculated by a simple numerical procedure, since the closed form solution is not available. In case of traction boundary conditions, the respective desingularized values of the derivatives of the fundamental solution in the coordinate directions, as required in the calculations, are calculated indirectly by considering two reference solutions of the linearly varying simple displacement fields. The feasibility and accuracy of the newly developed method are demonstrated through comparison with MFS solutions and analytical solutions for a spectra of anisotropic plane strain elasticity problems, including bi-material arrangements. NMFS turns out to give similar results as the MFS in all spectra of performed tests. The lack of artificial boundary is particularly advantageous for using NMFS in multi-body problems.


      PubDate: 2014-06-14T16:33:59Z
       
  • Transient 3D heat conduction in functionally graded materials by the
           method of fundamental solutions
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): Ming Li , C.S. Chen , C.C. Chu , D.L. Young
      In this paper, the three-dimensional transient heat conduction problems in functionally graded materials (FGMs) have been solved using the method of fundamental solutions (MFS). To be more specific, we consider the FGMs with thermal conductivity and specific heat vary exponentially in z-direction. In the numerical simulation, we coupled the fundamental solution of diffusion equation with the method of time–space unification which provides a simple and direct approach for solving time-dependent problems. The parameter transformation technique is also utilized to obtain the fundamental solutions which contain the thermal conductivity and the specific heat conditions. The MFS is very attractive in handling problems with irregular domain due to the simplicity of the method. The numerical results are in good agreement comparing with analytical solution and results obtained from the finite element method.


      PubDate: 2014-06-14T16:33:59Z
       
  • Solution of a continuous casting of steel benchmark test by a meshless
           method
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): R. Vertnik , B. Šarler
      This paper solves a recently proposed industrial benchmark test (Šarler et al., 2012 [1]) by a meshless method. The physical model is established on a set of macroscopic equations for mass, energy, momentum, turbulent kinetic energy, and dissipation rate in two dimensions. The mixture continuum model is used to treat the solidification system. The mushy zone is modeled as a Darcy porous media with Kozeny–Karman permeability relation, where the morphology of the porous media is modeled by a constant value. The incompressible turbulent flow of the molten steel is described by the Low-Reynolds-Number (LRN) k–ε turbulence model, closed by the Abe–Kondoh–Nagano closure coefficients and damping functions. The numerical method is established on explicit time-stepping, collocation with multiquadrics radial basis functions on non-uniform five-nodded influence domains, and adaptive upwinding technique. The velocity–pressure coupling of the incompressible flow is resolved by the explicit Chorin’s fractional step method. The advantages of the method are its simplicity and efficiency, since no polygonisation is involved, easy adaptation of the nodal points in areas with high gradients, almost the same formulation in two and three dimensions, high accuracy and low numerical diffusion. The results are carefully presented and tabulated, together with the results obtained by ANSYS-Fluent, which would in the future permit straightforward comparison with other numerical approaches as well.


      PubDate: 2014-06-14T16:33:59Z
       
  • Simulation of macrosegregation with mesosegregates in binary metallic
           casts by a meshless method
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): G. Kosec , B. Šarler
      Simulation of macrosegregation with mesosegregates as a consequence of solidification of a binary Sn–10%Pb alloy in a 2-dimensional rectangular cast is tackled in the present paper. Coupled volume averaged governing equations for mass, energy, momentum and species transfer are considered by incorporating Lever solidification rule and incompressible Newtonian fluid with Darcy limit in the mushy zone. Solid phase is assumed stationary. Double diffusive effects in the melt are modeled by the thermal and solutal Boussinesq hypothesis. The physical model is solved by the meshless Local Radial Basis Function Collocation Method (LRBFCM) by using 5-noded influence domains, multiquadrics radial basis functions and explicit time stepping. Pressure–velocity coupling is based on local pressure correction. Adaptive upwinding has to be used for stabilization of the convective terms. The numerical simulations reveal instabilities during solidification process that introduce anomalies in the final segregation map that scale with the typical cast as well as sub-cast dimensions. The main advantages of choosing the represented meshless approach for solving the problem are in its simplicity and similar coding in 2D and 3D, as well as straightforward applicability in non-uniform node arrangements. The locality of the proposed numerical approach is also convenient for parallel execution. It is demonstrated that LRBFCM can be advantageously used in casting simulations where the chemical segregation exhibits industrially relevant multi-scale patterns.


      PubDate: 2014-06-14T16:33:59Z
       
  • 3D Lattice Boltzmann flow simulations through dendritic mushy zones
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): A. Ludwig , A. Kharicha , C. Hölzl , J. Domitner , M. Wu , T. Pusztai
      Literature data on permeability of dendritic microstructures show a wide scatter. For a given solid fraction the permeability may vary easily by two orders of magnitude. This might be caused by some unavoidable technical problems in doing the corresponding experiments. However, even numerical results may vary greatly depending on the source of the input microstructure and/or the dimension of flow simulation (2D vs. 3D) and/or the applied boundary conditions. In the present work we have used the Lattice Boltzmann technique to perform flow simulations through 2D and 3D dendritic microstructures coming from (i) simplified geometrical approximations, (ii) phase field simulations of binary alloys and (iii) computer tomographs on AlCu alloys. The discussion of the results shows that for low solid fraction, simple geometries can be used as substitute for dendritic structures. However, once the secondary arms are more prominent, large deviations and scattering occur. These deviations are caused by the strong variation of the dendrites geometry along the growth direction, making simplified structures insufficient to derive a reasonable value for the permeability.


      PubDate: 2014-06-14T16:33:59Z
       
  • Coupled BEM–FEM analysis of flow and heat transfer over a solar
           thermal collector
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45
      Author(s): J. Ravnik , M. Hriberšek , L. Škerget
      A wavelet transform based BEM numerical scheme is used for Large Eddy Simulation of turbulent natural and forced convection of air flowing over a solar thermal collector. The collector is enclosed by vertical fins forming an open shallow cavity. The numerical scheme employs the velocity–vorticity formulation of Navier–Stokes equations using LES turbulence model where boundary element and finite element methods are combined. Grids with up to 2×105 nodes are used in simulations lasting for 6×104 time steps. Three inflow air velocities are considered corresponding to Reynolds number value up to 2 × 10 4 . Temperature difference between air and collector of about 50K is considered. Heat transfer from the thermal solar collector is studied via the average Nusselt number value, its time series and its relationship to the values of Reynolds and Rayleigh numbers. The results show that the largest heat losses occur behind the fin due to shedding of large vortices that transport hot air away from the collector. Heat losses decrease along the central part of the collector and feature another smaller peak just before the air hits the fin on the opposite side of the collector.


      PubDate: 2014-06-14T16:33:59Z
       
  • Variational multiscale element free Galerkin method for
           convection-diffusion-reaction equation with small diffusion
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): Xiaohua Zhang , Hui Xiang
      This paper presents the variational multiscale element free Galerkin method to solve convection-diffusion-reaction equation. The equation under consideration involves a small diffusivity and a large reaction coefficient, which leads to reaction-convection dominated problem. The variational multiscale element free Galerkin method is derived based on Hughes׳s variational multiscale formulation and element free Galerkin method, thus it inherits the advantages of variational multiscale and meshless methods, meanwhile, the formulation is free of any user-defined parameters owing to the stabilization parameter arises naturally. In order to investigate the presented method, both steady and unsteady 2D convection-diffusion-reaction problems are considered, and the numerical results illustrate the proposed method has the high accuracy and stability for solving convection-diffusion-reaction equation.


      PubDate: 2014-06-14T16:33:59Z
       
  • Editorial Board
    • Abstract: Publication date: August 2014
      Source:Engineering Analysis with Boundary Elements, Volume 45




      PubDate: 2014-06-14T16:33:59Z
       
  • Numerical solution of the t-version complex variable boundary integral
           equation for the interior region in plane elasticity
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): Y.Z. Chen
      This paper suggests the t-version complex variable boundary integral equation (CVBIE) for the interior region in plane elasticity. All the kernels in the t-version CVBIE are expressed explicitly. The property for the operator acting upon the displacement is studied. It is proved that there are three types of rigid mode movement of displacement for the t-version CVBIE, if the boundary is assumed under a traction free condition. Discretization of the t-version CVBIE is suggested. For the hypersingular integral, the integration is carried out exactly in the concept of Hadamard׳s finite part integral. Two particular examples which have known solution beforehand are used to examine the accuracy in computation. The Neumann and the Dirichlet boundary value problems are examined numerically. It is proved that the computation error is acceptable in the examples.


      PubDate: 2014-06-14T16:33:59Z
       
  • Optimal positioning of anodes and virtual sources in the design of
           cathodic protection systems using the method of fundamental solutions
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): W.J. Santos , J.A.F. Santiago , J.C.F. Telles
      The method of fundamental solutions (MFS) is used for the solution of Laplace׳s equation, with nonlinear boundary conditions, aiming at analyzing cathodic protection systems. In the MFS procedure, it is necessary to determine the intensities and the distribution of the virtual sources so that the boundary conditions of the problem are satisfied. The metallic surfaces, in contact with the electrolyte, to be protected, are characterized by a nonlinear relationship between the electrochemical potential and current density, called cathodic polarization curve. Thus, the calculation of the intensities of the virtual sources entails a nonlinear least squares problem. Here, the MINPACK routine LMDIF is adopted to minimize the resulting nonlinear objective function whose design variables are the coefficients of the linear superposition of fundamental solutions and the positions of the virtual sources outside the problem domain. First, examples are presented to validate the standard MFS formulation as applied in the simulation of cathodic protection systems, comparing the results with a direct boundary element (BEM) solution procedure. Second, a MFS methodology is presented, coupled with a genetic algorithm (GA), for the optimization of anode positioning and their respective current intensity values. All simulations are performed considering finite regions in R 2.


      PubDate: 2014-06-14T16:33:59Z
       
  • Transient free-surface seepage in three-dimensional general anisotropic
           media by BEM
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): K. Rafiezadeh , B. Ataie-Ashtiani
      Kinematic boundary condition is usually used when dealing with transient free-surface flow problems in isotropic media. When dealing with anisotropic problems, a transformation can transform the anisotropic media to an equivalent isotropic media for seepage analysis, but the kinematic boundary condition cannot be used directly in the transformed media. A generalization of the kinematic boundary condition along any arbitrary direction is derived for use in the transformed domain for general three-dimensional anisotropic problems. A boundary element method for solving transient free-surface seepage problems is developed and the treatment of the proposed kinematic boundary condition in the boundary element method is given. Three examples have been solved to show the reliability and flexibility of the model. Examples are verified with some available experimental and numerical cases to show the accuracy of the model for predicting the phreatic surface and it is shown that anisotropy has a very important and non-neglecting effect in the behavior and the shape of phreatic surface.


      PubDate: 2014-06-14T16:33:59Z
       
  • The numerical manifold method for elastic wave propagation in rock with
           time-dependent absorbing boundary conditions
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): Zhijun Wu , Lifeng Fan
      In this study, a modified first-order Higdon׳s absorbing boundary scheme is proposed and incorporated into the numerical manifold method (NMM) to reduce reflections from artificial boundaries induced by truncating infinite media. The modified time-dependent absorbing boundary scheme can not only consider the absorbing boundary and input boundary at the same artificial boundary, but also take the effects of the incident angles into consideration by adjusting the velocities and strains of points at the boundary automatically. For illustrating the efficiency of the proposed time-dependent absorbing boundary scheme, comparisons between the results of the proposed method and the widely used viscous boundary conditions for different incident angles are presented. The developed NMM is then used to investigate wave attenuation and transmission across a joint in an infinitely long rock bar.


      PubDate: 2014-06-14T16:33:59Z
       
  • A comparison of the meshless RBF collocation method with finite element
           and boundary element methods in neutron diffusion calculations
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): T. Tanbay , B. Ozgener
      The multigroup neutron diffusion equation is solved numerically by the meshless radial basis function collocation and mesh-based finite and boundary element methods. For the collocation method, multiquadrics, inverse multiquadrics and Gaussian basis functions are utilized, whereas linear shape functions are the choice for finite and boundary element methods. External and fission source problems are studied. In the context of external source case, constant, trigonometric, and linear sources are considered. The collocation method converges exponentially which is faster than the algebraic rates of finite and boundary element methods for both problems, and it was found that by adjusting the value of the shape parameter, very high accuracies can be achieved even with large fill distances. In the fission source case, multiquadrics is found to be superior to finite and boundary elements for the determination of multiplication factor, while boundary elements gave the best result for group fluxes. A comparison of CPU times shows that, finite element method has outperformed radial basis function collocation and boundary elements. When the stability is considered, finite and boundary element methods have the advantage of being more stable than the collocation technique.


      PubDate: 2014-06-14T16:33:59Z
       
  • Nonlinear solution of the PS model for a semi-permeable crack in a 3D
           piezoelectric medium
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): CuiYing Fan , HuaYang Dang , MingHao Zhao
      By considering the electric field in the crack cavity, the polarization saturation (PS) model of a penny-shaped crack under electrically semi-permeable boundary condition in a three-dimensional piezoelectric medium is studied via both the extended displacement discontinuity boundary integral equation method and the boundary element method. An approximate analytical solution is derived, and the electric displacement in the crack cavity, the electric yielding zone and the local J-integral are obtained. The extended displacement discontinuity boundary element method with double iterative approaches is adapted to numerically simulate the electrically semi-permeable crack and to validate the analytical solution. The effects of different boundary conditions on the electric yielding zone and the local J-integral are also investigated.


      PubDate: 2014-06-14T16:33:59Z
       
  • New approximation functions in the meshless finite volume method for 2D
           elasticity problems
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): M. Ebrahimnejad , N. Fallah , A.R. Khoei
      In this paper, two new approximation functions are introduced. These new techniques, which are referred herein as the multi-triangles method (MTM) and weighted multi-triangles method (WMTM) are applied for the approximation of unknowns and their derivatives at the points of interest. The approximations are performed in terms of the unknowns corresponding to the field nodes which are the vertices of the region surrounding the desired point and determined by Delaunay triangulations. The capability and accuracy of the proposed approximation functions are compared with the other approximating techniques in the meshless finite volume (MFV) frame work for some benchmark problems. Numerical examples reveal the superiority of the WMTM and MTM over the common moving least squares technique (MLS) and radial point interpolation method (RPIM) for the same number of nodes in the support domain. Moreover, the suggested methods need less computational time especially when dense field nodes are applied.


      PubDate: 2014-06-14T16:33:59Z
       
  • Analysis of heat flux singularity at 2D notch tip by singularity analysis
           method combined with boundary element technique
    • Abstract: Publication date: September 2014
      Source:Engineering Analysis with Boundary Elements, Volume 46
      Author(s): Changzheng Cheng , Zhilin Han , Shanlong Yao , Zhongrong Niu , Naman Recho
      It is known that the heat flux becomes infinite near the notch tip due to material or geometric discontinuities. Numerical methods such as boundary element method and finite element method cannot adequately analyze the accurate singular heat flux field since they traditionally employ piecewise polynomials. In this paper, the singularity analysis method coupled with the boundary element technique is proposed for the accurate analysis of two-dimensional singular heat flux field near the notch tip. The V-notched structure is departed into two parts, which are the near tip singular sector and far tip non-singular section. The singularity analysis is executed on the near notch tip sector for searching singularity orders and corresponding characteristic angular functions by introducing the heat flux asymptotic expansions into heat conduction governing equations. The conventional boundary element method is applied to modeling the far notch tip region because there is no heat flux singularity. The asymptotic expansions of the near tip physical field and the boundary integral equations established on the far notch tip region are combined together for solving the expansion coefficients in heat flux asymptotic expansions. Thus, the complete heat flux field near the notch vertex can be accurately determined.


      PubDate: 2014-06-14T16:33:59Z
       
  • Inverse scattering analysis of an elastic half-space by means of the fast
           volume integral equation method
    • Abstract: Publication date: Available online 14 March 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): Terumi Touhei , Takuya Hinago , Yasufumi Fukushiro
      A method for inverse scattering analysis of an elastic half-space using the fast volume integral equation method is presented. For the formulation of the inverse scattering analysis, the volume integral equation for the forward scattering analysis is modified so that it describes the relationship between the observed scattered waves at the free surface and the fluctuation of the wavefield. The inversion equation is obtained for reconstructing spatial spreads and the amplitude of fluctuations of the wavefield from the observed scattered waves due to point sources at the free surface. Linearization by the Born approximation as well as the Tikhonov regularization method is applied to the inversion equation. The fast generalized Fourier transform is also applied in order to solve the inversion equation. Numerical calculations are performed in order to investigate the convergence properties of the solution with respect to different regularization parameters. In addition, the effects of the number of point sources on the accuracy of the reconstruction results are examined.


      PubDate: 2014-04-29T06:47:23Z
       
  • Force–moment line element method for Stokes flow around a slender
           body
    • Abstract: Publication date: Available online 15 March 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): H. Jiang , Y.T. Wu , B. Yang , Y.-P. Zhao
      We present a higher-order line element method for Stokes flow around a slender body by taking into account effects of both net force and couple moment densities along its center line. The numerical technique is based on a line integral equation, which in turn is derived by reducing from a boundary integral equation of Stokes flow. The line integral equation of velocity gradient is employed along with that of velocity to close the formulation. Numerical examples of rigid slender bodies are presented to demonstrate the capability and validity of the present method, including passive motion of a slender body suspended in a simple shear flow and active motion of a slender body driven by a body moment. In the first case, it is shown that the moment density due to shear rigidity mismatch between the fluid and solid can be finite. Meanwhile, the transverse net force density is rather induced by a small velocity lag due to the impeding moment density component. Effects of slip and no-slip interfacial conditions are examined, showing their important role in determining the slender-body hydrodynamics. The present force–moment line element method provides a capable tool for solving the problems of strong and weak interactions between a slender body and a viscous fluid at low Reynolds number.


      PubDate: 2014-04-29T06:47:23Z
       
  • A model-integrated localized collocation meshless method for large scale
           three-dimensional heat transfer problems
    • Abstract: Publication date: Available online 29 March 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): S. Gerace , K. Erhart , A. Kassab , E. Divo
      We present a Model Integrated Meshless Solver (MIMS) tailored to solve practical large-scale industrial problems. This is accomplished by developing a robust meshless technique as well as a comprehensive model generation procedure. By closely integrating the model generation process into the overall solution methodology, the presented techniques are able to fully exploit the strengths of the meshless approach to achieve levels of automation, stability, and accuracy currently unseen in the area of engineering analysis. Specifically, MIMS implements a blended meshless solution approach which utilizes a variety of shape functions to obtain a stable and accurate iteration process. This solution approach is then integrated with a newly developed, highly adaptive model generation process which employs a quaternary triangular surface discretization for the boundary, a binary-subdivision discretization for the interior, and a unique shadow layer discretization for near-boundary regions. Together, these discretization techniques are able to achieve directionally independent, automatic refinement of the underlying model, allowing the method to generate accurate solutions without the need for intermediate human involvement. In addition, by coupling the model generation with the solution process, the presented method is able to address the issue of ill-constructed geometric input such as small features, poorly formed faces, and other such pathologies often generated from solid models in the course of design and in the end to provide an intuitive, yet powerful approach to solving modern engineering analysis problems.


      PubDate: 2014-04-29T06:47:23Z
       
  • Mesh reduction methods for industrial applications
    • Abstract: Publication date: Available online 3 April 2014
      Source:Engineering Analysis with Boundary Elements
      Author(s): Božidar Šarler



      PubDate: 2014-04-29T06:47:23Z
       
  • Application of the Trefftz method, on the basis of Stroh formalism, to
           solve the inverse Cauchy problems of anisotropic elasticity in multiply
           connected domains
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Tao Zhang , Leiting Dong , Abdullah Alotaibi , Satya N. Atluri
      In this paper, the Trefftz collocation method is applied to solve the inverse Cauchy problem of anisotropic elasticity, wherein both tractions as well as displacements are prescribed at a small part of the boundary of an arbitrary simply/multiply connected anisotropic elastic domain. The Stroh formalism is used to construct the Trefftz basis functions. Negative and positive power series are used together with conformal mapping to approximate the complex potentials of the Stroh formalism. For inverse problems where noise is present in the measured data, Tikhonov regularization is used together with the L-curve parameter selection method, in order to mitigate the inherent ill-posed nature of inverse problems. By several numerical examples, we show that this simple and elegant method can successfully solve inverse problems of anisotropic elasticity, with noisy measurements, in both simply and multiply connected domains.


      PubDate: 2014-04-29T06:47:23Z
       
  • A highly efficient multidomain BEM for multimillion subdomains
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Matjaž Ramšak , Leopold Škerget
      This paper presents a 2D multidomain boundary element method (BEM) for potential problems using mixed boundary elements. The aim of the paper is to test the developed numerical method for solving multimillion DOFs under extreme conditions: high element aspect ratios and high conductivity ratios. The double precision for the system matrix was found to be necessary for the solution for multimillion DOFs. The accuracy, robustness, and efficiency of the developed BEM are demonstrated by solving a nine million node mesh within a few days. A one million node mesh is solved in 1h using a 3.4GHz personal computer and 3GB of memory in double precision. The main numerical example is heat diffusion in the intricate fractal geometry of the Koch snowflake.


      PubDate: 2014-04-29T06:47:23Z
       
  • Boundary element analysis of multi-thickness shear-deformable slabs
           without sub-regions
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Mina Wagdy , Youssef F. Rashed
      In this paper, a new boundary element formulation is developed for the analysis of multi-thickness slabs. The shear deformable plate bending theory is employed. The additional thickness is added to the plate using additional stiffness matrix. A new systematic methodology for deriving stiffness matrix of additional thicknesses or drops is presented. The formulation is implemented into a computer code and several examples are considered to demonstrate the validity of the presented formulation.


      PubDate: 2014-04-29T06:47:23Z
       
  • Boundary element simulation of fatigue crack growth in multi-site damage
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): R.J. Price , J. Trevelyan
      This paper presents an efficient and automatic scheme for modelling the growth of multiple cracks through a two-dimensional domain under fatigue loading based on linear elastic fracture mechanics. The dual boundary element method is applied to perform an analysis of the cracked domain and the J-integral technique is used to compute stress intensity factors. Incremental crack propagation directions are evaluated using the maximum principal stress criterion and a combined predictor–corrector algorithm implemented for propagation angle and increment length. Criteria are presented to control the mesh used on the slower growing cracks in the domain, improving computational efficiency and accuracy by the use of virtual crack tips to avoid the need for severe mesh grading. Results are presented for several geometries with multi-site damage, and sensitivity to incremental crack length is investigated. The scheme demonstrates considerable advantages over the finite element method for this application due to simplicity of meshing, and over other boundary element formulations for modelling domains with large ranges of crack growth rates.


      PubDate: 2014-04-29T06:47:23Z
       
  • Application of a hybrid mesh-free method for shock-induced thermoelastic
           wave propagation analysis in a layered functionally graded thick hollow
           cylinder with nonlinear grading patterns
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Seyed Mahmoud Hosseini
      This article exploits a hybrid mesh-free method for coupled thermoelasticity analysis (without energy dissipation) and thermoelastic wave propagation analysis in layered FGMs subjected to shock loading. The presented hybrid mesh-free method is based on generalized finite difference (GFD) and Newmark finite difference (NFD) methods. The Green–Naghdi (GN) theory of coupled thermoelasticity is assumed to derive the governing equations for FG thick hollow cylinder. The layered FG cylinder is assumed to be under thermal shock loading. The mechanical properties of layered FG cylinder are considered to vary along the radial direction as nonlinear functions in terms of volume fraction. Thermoelastic wave propagations are studied in details at various time instants for various grading patterns of mechanical properties. The effects of nonlinear grading patterns on thermoelastic wave propagations are obtained and discussed using the presented effective mesh-free method.


      PubDate: 2014-04-29T06:47:23Z
       
  • Convolution quadrature methods for 3D EM wave scattering analysis
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Amir Geranmayeh
      The time-domain boundary integral equations describing the electromagnetic wave scattering from arbitrary three-dimensional metallic structures are solved by applying spectral domain finite-difference approximations while mapping from the Laplace domain to the z-transform domain. The validity of the results are verified through comparison with high-resolution finite difference time domain method results and the convergence rate of the introduced time-marching schemes is compared with the time basis functions expansion methods.


      PubDate: 2014-04-29T06:47:23Z
       
  • Cover refinement of numerical manifold method for crack propagation
           simulation
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Shikou Yang , Guowei Ma , Xuhua Ren , Feng Ren
      A cover refinement method is proposed for the numerical manifold method (NMM) to simulate crack propagation in brittle materials. New mathematical covers are defined for manifold elements near a crack tip. The refinement is done for corresponding mathematical covers of the selected manifold elements. The updating process of mathematical cover with respect to different boundary conditions is introduced in detail. When a mathematical cover is updated, the corresponding physical covers and manifold elements are updated accordingly. Furthermore, the loops of the considered domain are updated as well. Three numerical examples are analyzed to validate the proposed cover refinement method. The numerical results are all in good agreement with those results in the existing studies. It is demonstrated that the proposed cover refinement method has higher accuracy for crack propagation simulation comparing to the traditional numerical manifold method which has a consistent mathematical cover system. The proposed cover refinement method also does not significantly change the manifold elements at the vicinity of the crack tips. A rock slope model with a bilinear failure mode is simulated and progressive failure process of the rock slope is obtained, which demonstrates the applicability of the proposed method in practical rock engineering.


      PubDate: 2014-04-29T06:47:23Z
       
  • Acoustic eigenanalysis of 2D open cavity with Vekua approximations and the
           method of particular solutions
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Alexandre Leblanc , Gilles Chardon
      This paper discusses the efficient extraction of acoustic resonances in 2D open cavities using a meshless method, the method of particular solutions. A first order, local non-reflecting boundary condition is chosen to account for the opening and Fourier-Bessel functions are employed to approximate the pressure at the borders of the cavity and inside. A minimization problem is then solved for the complex frequency range of interest. For the investigated cavity, the minimum values obtained match those found in previously published studies or by other numerical methods. But, unlike the perfectly matched layer absorbing boundary conditions now usually employed, this approach is free from spurious eigenfrequencies. Moreover, the specific treatments of the geometric singularities allow this method to be particularly efficient in the presence of corner singularities.


      PubDate: 2014-04-29T06:47:23Z
       
  • Fully enriched weight functions in mesh-free methods for the analysis of
           linear elastic fracture mechanics problems
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): Reza Namakian , Hossein M. Shodja , Mohammad Mashayekhi
      The so-called enriched weight functions (EWFs) are utilized in mesh-free methods (MMs) to solve linear elastic fracture mechanics (LEFM) problems; the following issues are of concern: convergence behavior; sufficiency of EWFs to capture singular fields around the crack-tip; and the preservation of the J-integral path-independency. EWFs prove useful in conjunction with the moving least square reproducing kernel method (MLSRKM); for this purpose, both EWFs and MLSRKM are modified. Since EWFs are not truly representative of the near-tip solution, fully EWFs (FEWFs) are introduced. Finally, some descriptive examples address the aforementioned concerns and the accuracy and efficacy of the proposed technique.


      PubDate: 2014-04-29T06:47:23Z
       
  • A 2D BEM–FEM approach for time harmonic fluid–structure
           interaction analysis of thin elastic bodies
    • Abstract: Publication date: June 2014
      Source:Engineering Analysis with Boundary Elements, Volume 43
      Author(s): J.D.R. Bordón , J.J. Aznárez , O. Maeso
      This paper deals with two-dimensional time harmonic fluid–structure interaction problems when the fluid is at rest, and the elastic bodies have small thicknesses. A BEM–FEM numerical approach is used, where the BEM is applied to the fluid, and the structural FEM is applied to the thin elastic bodies. From the fluid point of view, the thin elastic bodies are considered of null thickness. This assumption is treated using simultaneously the Singular Boundary Integral Equation and the Hypersingular Boundary Integral Equation. It is assumed that the thin elastic bodies are under the Euler–Bernoulli hypotheses with added rotational inertia. The BEM equations (fluid) and the FEM equations (thin bodies) are coupled using appropriate equilibrium and compatibility conditions. The developed BEM–FEM model requires a simple discretization and leads to a small number of degrees of freedom, although it has some limitations that are studied in some depth. This approach is validated with existing results in the field of sound barriers, and new results using complex barrier shapes are presented. Also, a parametric study about a straight wall immersed in a fluid is done, which provides results of practical usage.


      PubDate: 2014-04-29T06:47:23Z
       
 
 
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