Mikael A. Langthjem¹, Masami Nakano²

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.4, pp. 227-241, 2013, DOI:10.3970/cmes.2013.096.227

Abstract This paper is concerned with a mathematical model of a simple axisymmetric silencer-like model, consisting of a hole-tone feedback system equipped with a tailpipe. The unstable shear layer is modeled via a discrete vortex method, based on axisymmetric vortex rings. The aeroacoustic model is based on the Powell- Howe theory of vortex sound. Boundary integrals are discretized via the boundary element method; but the tailpipe is represented by the exact (one-dimensional) solution. It is demonstrated though numerical examples that this numerical model can display lock-in of the self-sustained flow oscillations to the resonant acoustic oscillations. More >

A. Sellier

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.3, pp. 159-176, 2013, DOI:10.3970/cmes.2013.096.159

Abstract The rigid-body migration of a slip and arbitrary-shaped solid particle freely suspended in a prescribed and arbitrary ambient Stokes flow is determined after calculating the hydrodynamic force and torque exerted on the particle when it either experiences a given rigid-body in a quiescent liquid or is held fixed in the ambient Stokes flow. It is also shown how one can subsequently obtain the velocity and surface traction on the particle boundary and thereafter, if necessary, the flow about the particle in the entire liquid domain. The advocated procedure extends a recent work (see Sellier (2012)) More >

L. Rodríguez-Tembleque¹, A. Sáez¹, F.C. Buroni¹

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 131-158, 2013, DOI:10.3970/cmes.2013.096.131

Abstract A boundary element based formulation is applied to study numerically the tribological behavior of fiber-reinforced plastics (FRP) under different frictional contact conditions, taking into account the micromechanics of FRP. Micromechanical models presented consider continuous and short fiber reinforced plastics configurations. The Boundary Element Method (BEM) with an explicit approach for fundamental solutions evaluation is considered for computing the elastic influence coefficients. Signorini’s contact conditions and an orthotropic law of friction on the potential contact zone are enforced by contact operators over the augmented Lagrangian. The proposed methodology is applied to study carbon FRP under frictional More >

A. F. Galvis¹, R. Q. Rodriguez¹, P. Sollero¹, E. L. Alburquerque²

CMES-Computer Modeling in Engineering & Sciences, Vol.96, No.2, pp. 103-115, 2013, DOI:10.3970/cmes.2013.096.103

Abstract Polycrystalline structures are present on metal alloys. Therefore, it is necessary to understand and model the mechanical behavior of this media. Usually, this is accomplished by the use of different numerical methods. However, the analysis of polycrystalline materials leads to other type of problems, such as high computational requirements generated in order to get an efficient solution. In this work, the 2D polycrystalline structure is generated using an average grain size through the Voronoi tessellation method and discretized through simulations with random material, crystalline orientation and orthotropic behavior [Sfantos and Aliabadi (2007a)]. BEM discretization requires More >

M. G. He¹, C.L. Tan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.4, pp. 317-349, 2013, DOI:10.3970/cmes.2013.095.315

Abstract The self-regularization technique in the Boundary Element Method (BEM) originally proposed by Cruse and Richardson (1996, 1999) in their work for two-dimensional (2-D) stress analysis is extended to three-dimensional (3-D) elastostatics in this paper. The regularization scheme addresses the issue of accurate numerical evaluation of the integrals due to the singularity of the kernel functions of the integral equations. It is first implemented for the determination of displacements and stresses at interior points of the solution domain, and very accurate results are obtained even when these points are very close to the surface of the More >

Hongtao Wang^1,2, Haitao Wang², Lie Jin², Zhenhan Yao³

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.6, pp. 529-552, 2013, DOI:10.3970/cmes.2013.094.529

Abstract Since only the boundary of the analyzed domain needs to be discretized, the boundary element method (BEM) inherently has the advantages of solving crack problems. In this paper, a micromechanics BEM scheme is applied to determine the effective elastic moduli of three-dimensional (3-D) solids containing a large number of parallel or randomly oriented microcracks. The 3-D analyses accelerated by the fast multipole method were carried out to investigate the relations between the effective elastic moduli and the microcrack density parameter. Numerical examples show that the results agree well with the available analytical solution and known More >

Guizhong Xie¹, Jianming Zhang^1,2, Cheng Huang¹, Chenjun Lu¹, Guangyao Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.2, pp. 139-157, 2013, DOI:10.3970/cmes.2013.094.139

Abstract In this work, an improved exponential transformation is presented for nearly singular boundary element integrals in problems of thin structures. Accurate evaluation of nearly singular integrals is an important issue in the implementation of boundary element method (BEM) for thin structures. In this paper, the exponential transformation, which was firstly developed to evaluate nearly singular integrals arising in 2D BEM, is extended into 3D BEM to deal with nearly singular integrals. Firstly, a novel (α,β) coordinate system is introduced. Then, the conventional distance function is modified into a new form in (α,β) coordinate system. Based More >

A. Tadeu¹, P. Stanak², J. Sladek², V. Sladek², J. Prata¹, N. Simões¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.6, pp. 489-516, 2013, DOI:10.3970/cmes.2013.093.489

Abstract This paper presents a technique that couples the boundary element method (BEM) with the meshless local Petrov-Galerkin (MLPG) method, formulated in the frequency domain. It is then used to study the transient heat diffusion through a two-dimensional unbounded medium containing confined subdomains where the material properties vary from point to point. To exploit the advantages of each method, the BEM is used for the homogeneous unbounded domain and the MLPG method is used for the non-homogeneous confined subdomains. The nodal points placed at the interface between the confined subdomains and the unbounded homogenous medium are… More >

J.H. Lv¹, Y. Miao^1,2, W.H. Gong¹, H.P. Zhu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.2, pp. 113-131, 2013, DOI:10.3970/cmes.2013.093.113

Abstract Accurate numerical evaluation of the nearly singular boundary integrals is a major concerned issue in the implementation of boundary element method (BEM). In this paper, a general distance function independent on the nearly singular point is proposed. Combined with an iteration process, the position of the nearly singular point can be obtained more easily. Then, an extended form of the sinh transformation using the general distance function, which automatically takes into account the intrinsic coordinate of the nearly singular point and the minimum distance from source point to the element in the intrinsic parameter plane, More >

L.Q. Liu¹, H.T. Wang^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.6, pp. 439-462, 2013, DOI:10.3970/cmes.2013.090.439

Abstract A line model-based fast boundary element method (BEM) is presented for the large-scale cathodic protection (CP) analysis of three-dimensional pipelines in layered soils. In this approach, pipelines are treated as lines with potentials assumed constant over the cross-section and the boundary integrals happen on the associated cylindrical surfaces. The advantage of this model is that pipelines can be meshed with line elements while the boundary integrals are based on the original shapes. Therefore, the number of unknowns is significantly reduced with accuracy effectively retained. A unified formulation of the multipole moments is developed for the More >