Qi Zhou¹, Xinyu Shao¹, Ping Jiang^1,2, Longchao Cao¹, Hui Zhou¹, Leshi Shu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.5, pp. 323-355, 2015, DOI:10.3970/cmes.2015.106.323

Abstract Computational simulation models with different fidelity have been widely used in complex systems design. However, running the most accurate simulation models tends to be very time-consuming and can therefore only be used sporadically, while incorporating less accurate, inexpensive models into the design process may result in inaccurate design alternatives. To make a trade-off between high accuracy and low expense, variable fidelity (VF) metamodeling approaches that aim to integrate information from both low fidelity (LF) and high-fidelity (HF) models have gained increasing popularity. In this paper, a Difference Mapping Framework using Ensemble of Metamodels (DMF-EM) for… More >

Xu Yong^1,2, Feng Jing¹, Xu Wei¹, Gu Rencai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.5, pp. 309-322, 2015, DOI:10.3970/cmes.2015.106.309

Abstract In this paper, bifurcation analysis and numerical simulations are performed on the FitzHugh-Nagumo system in the presence of Lévy stable noise. The stationary probability density functions are obtained to examine the influences of noise intensity and stability index. Results show that under the influences of noise intensity and stability index, the dynamic of the FitzHugh-Nagumo model can be well characterized through the concept of stochastic bifurcation, consisting in qualitative changes of the stationary probability distribution. Then, the mean passage time between the resting and action state is investigated as functions of noise intensity and stability More >

Joo Shin Park¹, Jung Kwan Seo^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.4, pp. 291-308, 2015, DOI:10.3970/cmes.2015.106.291

Abstract Ships, ship-shaped offshore structures, land-based structures and aerospace structures typically consist of various curved plate components. It is difficult to simulate the buckling and post-buckling of curved thin and/or thick plates that have characteristics of nonlinear structural mechanics, such as nonlinear behaviour when loading is applied. The elastic post-buckling behaviour of a curved plate is very complex, and accompanied by mode changes due to the occurrence of secondary buckling behaviour. Therefore, it is very important to clarify the elastic post-buckling behaviour when subjected to axial loading. The aim of this study was to derive an More >

Jinghua Wang¹, S Yan¹, Q.W. Ma^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.4, pp. 263-289, 2015, DOI:10.3970/cmes.2015.106.263

Abstract This paper presents an improved technique to generate rogue (freak) waves embedded in random sea based on the approach proposed by Kribel and Alsina (2000). In this method, a part of the wave energy is focused using the temporal-spatial focusing approach to generate an extreme transient wave and the rest behaves randomly. By introducing a correction term, the improved technique removes the numerical.ly spurious fluctuations of the spectra in the existing approach. Various effects of the correction are investigated numerically by using the second-order wave theory and two existing numerical. methods based on the fully More >

Jan Sladek¹, Vladimir Sladek¹, Peter Stanak¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.4, pp. 229-262, 2015, DOI:10.3970/cmes.2015.106.229

Abstract The scaled boundary finite element method (SBFEM) is presented to study thermoelastic problems in materials with voids. The SBFEM combines the main advantages of the finite element method (FEM) and the boundary element method (BEM). In this method, only the boundary is discretized with elements leading to a reduction of spatial dimension by one. It reduces computational efforts in mesh generation and CPU. In contrast to the BEM, no fundamental solution is required, which permits to analyze general boundary value problems, where the conventional BEM cannot be applied due to missing fundamental solution. The computational More >

M. Wasserman^1,2, Y. Mor-Yossef^1,2, J.B. Greenberg¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 203-228, 2015, DOI:10.3970/cmes.2015.106.203

Abstract A test problem of a laminar edge flame formed in the mixing layer of two initially separated streams of fuel and oxidant is employed to evaluate the performance of multigrid acceleration of the iterative solution of the central difference finite difference scheme approximating the governing energy and species mass fraction conservation equations. The multigrid method was found to be extremely efficient and significantly improved the iterative convergence relative to that of a single grid method. For low to moderate chemical Damkohler numbers, acceleration factors of up to six (6!) times were recorded in the computational… More >

Hui Huang, Hidekazu Murakawa

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 187-201, 2015, DOI:10.3970/cmes.2015.106.187

Abstract Dynamic mesh refining method (DMRM) developed previously was extended to multi-level refinement, and employed to perform thermal-mechanical analysis of fillet welding. The DMRM has been successfully incorporated with another efficient technique, the iterative substructure method (ISM) to greatly enhance the computation speed of welding simulation. The basic concept, hierarchical modeling and computation flowchart are described for the proposed method. A flange-to-pipe welding problem has been solved with a commercial code and the novel method to demonstrate its high accuracy and efficiency. Furthermore, the numerical analysis was performed on a large scale stiffened welding structure, and More >

K. Kuramoto¹, M. Furuichi², K. Kakuda²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 169-186, 2015, DOI:10.3970/cmes.2015.106.169

Abstract This paper describes a scheme to improve efficiency of multi-agent simulation system (MAS) on single computer that has multiple processor cores. Simulation technology is applied for broad usage in the world, and MAS gathers attention from the fields that treat complicated and non-numeric issues such as traffic analysis, analyzing evacuation from a building, and defense training. Since the requirements of simulation scale and fidelity are growing, the importance of their performance is also increasing. However, CPU clock speedup is slowing, and improvement of computer performance has come to depend on the number of processors, cores,… More >

S. Masuri¹, K. K. Tamma²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 147-168, 2015, DOI:10.3970/cmes.2015.106.147

Abstract The objective in this paper is to extend the previously developed twoparameter GS4-1 (Generalized Single System Single Solve for 1st order transient systems) computational framework from parabolic to hyperbolic type of applications pertaining to first order linear transient systems. In particular, attention is paid to the selective control feature inherit in the framework, which is the new feature that enables different amounts of high frequency damping for the primary variable and its time derivative, allowing for physically accurate solutions of all variables in the system. This is in contrast to having only limited, often indiscriminate, More >

J. E. Sebold¹, L. A. Lacerda², J. A. M. Carrer³

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.2, pp. 127-145, 2015, DOI:10.3970/cmes.2015.106.127

Abstract This paper deals with a Finite Element Method (FEM) for the approximation of the Helmholtz equation for two dimensional problems. The acoustic boundary conditions are weakly posed and an auxiliary problem with homogeneous boundary conditions is defined. This auxiliary approach allows for the formulation of a general solution method. Second order finite elements are used along with a discretization parameter based on the fixed wave vector and the imposed error tolerance. An explicit formula is defined for the mesh size control parameter based on Padé approximant. A parametric analysis is conducted to validate the rectangular More >