J. X. Zhou¹, T. Koziara¹, T. G. Davies¹

CMES-Computer Modeling in Engineering & Sciences, Vol.16, No.2, pp. 131-140, 2006, DOI:10.3970/cmes.2006.016.131

Abstract The classical BEM approach for elastodynamics can produce poor results when high gradients are generated by impulses. High gradient areas evolve over time and their locations are unknown a priori, so they usually can not be captured by uniform meshes. In this paper, we propose a novel method which interpolates both spatial and temporal domains. A direct space-time discretization scheme is used to capture the wave fronts accurately and to forestall generation of spurious oscillations there. Some numerical examples are given to demonstrate the power and scope of the method. More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.3, pp. 197-212, 2006, DOI:10.3970/cmes.2006.012.197

Abstract In this paper we numerically solve the Burgers equation by semi-discretizing it at the n interior spatial grid points into a set of ordinary differential equations: u^· = f(u,t), u ∈ Rⁿ. Then, we take the dissipative behavior of Burgers equation into account by considering the magnitude ||u|| as another component; hence, an augmented quasilinear differential equations system X^˙ = AX with X := (u^T,||u||)^T ∈ Mⁿ⁺¹ is derived. According to a Lie algebra property of A∈so(n,1) we thus develop a new numerical scheme with the transformation matrix G∈SO_o(n,1) being an element of the proper orthochronous Lorentz group.… More >

R. Ahrem¹, A. Beckert², H. Wendland³

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.2, pp. 121-136, 2006, DOI:10.3970/cmes.2006.012.121

Abstract We present a new efficient scheme for loose coupling in fluid-structure-interaction problems as they typically appear in the context of aircraft design. This coupling scheme is based upon a multivariate scattered data interpolation approach, based on radial basis functions and partition of unity methods. It allows us to couple arbitrary meshes on fluid and structure side. It conserves virtual work and forces. It is designed for large scale problems and allows the coupling of entire aircraft meshes. More >

P.H. Gaskell¹, Y.C. Lee², H.M. Thompson¹

CMES-Computer Modeling in Engineering & Sciences, Vol.62, No.1, pp. 77-112, 2010, DOI:10.3970/cmes.2010.062.077

Abstract The three-dimensional flow of a gravity-driven continuous thin liquid film on substrates containing micro-scale features is modelled using the long-wave lubrication approximation, encompassing cases when surface topography is either engulfed by the film or extends all the way though it. The discrete analogue of the time-dependent governing equations is solved accurately using a purpose designed multigrid strategy incorporating both automatic error-controlled adaptive time stepping and local mesh refinement/de-refinement. Central to the overall approach is a Newton globally convergent algorithm which greatly simplifies the inclusion of further physics via the solution of additional equations of the same form as the base… More >

R. Avila¹, S. N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.1, pp. 15-64, 2009, DOI:10.3970/cmes.2009.054.015

Abstract The Meshless Local Petrov Galerkin (MLPG) method is used to solve the non-steady two dimensional Navier-Stokes equations. Transient laminar flow field calculations have been carried out in domains wherein certain surfaces have: (i) a sliding motion, (ii) a harmonic motion, (iii) an undulatory movement, and (iv) a contraction-expansion movement. The weak form of the governing equations has been formulated in a Cartesian coordinate system and taking into account the primitive variables of the flow field. A fully implicit pressure correction approach, which requires at each time step an iterative process to solve in a sequential manner the equations which govern… More >

Chein-Shan Liu¹, Li-Wei Liu², Hong-Ki Hong²

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.1, pp. 1-18, 2007, DOI:10.3970/cmes.2007.017.001

Abstract In this paper we are concerned with the parameters identification of the inverse heat conduction problems governed by linear parabolic partial differential equations (PDEs). It is the first time that one can construct a closed-form estimation method for the inverse thermal problems of estimating the spatial-dependent thermophysical parameters. The key points hinge on an establishment of a one-step group preserving scheme (GPS) for the semi-discretization of PDEs, as well as a closed-form solution of the resulting algebraic equations. The new method, namely the Lie-group estimation method, has four advantages: it does not require any prior information on the functional forms… More >

P.B. Béda¹

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 231-238, 2003, DOI:10.3970/cmes.2003.004.231

Abstract The paper studies the behavior of a spatial Euler-Bernoulli beam loaded by a terminal thrusting force and a couple. The classical Clebsch-Kirchhoff equilibrium equations are written by using appropriate angular coordinates describing the finite rotations of the local frames attached to each cross-sections of the beam with respect to a fixed system. When we have geometric boundary conditions at one end and dynamic boundary conditions (a force and a couple) at the other the set of equilibrium equations form and initial value probem which can easily be solved with standard Runge-Kutta method. More >

António Tadeu, Julieta António¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.4, pp. 477-496, 2001, DOI:10.3970/cmes.2001.002.477

Abstract This paper presents analytical solutions, together with explicit expressions, for the steady state response of homogeneous three-dimensional layered acoustic and elastic formations subjected to a spatially sinusoidal harmonic line load. These formulas are theoretically interesting in themselves and they are also useful as benchmark solutions for numerical applications. In particular, they are very important in formulating three-dimensional elastodynamic problems in layered fluid and solid formations using integral transform methods and/or boundary elements, avoiding the discretization of the solid-fluid interfaces. The proposed Green's functions will allow the solution to be obtained for high frequencies, for which the conventional boundary elements' solution… More >

Zhiliang Wang^1,*, Youpeng Huang¹, Feng Xiong¹

CMC-Computers, Materials & Continua, Vol.60, No.3, pp. 1189-1206, 2019, DOI:10.32604/cmc.2019.04972

Abstract This article reports numerical results investigating the damage evolution and spatial distribution characteristics of intact and jointed rockmass subjected to blast loading. The behaviors of rock material are described by the Holmquist- Johnson-Cook (HJC) constitutive model incorporated in the finite element software LS-DYNA. Results indicate that the damage distribution shows a reverse S-shape attenuation with the increase of the distance from borehole, and a better goodness of fit with the Logistic function is observed. In the single-hole blasting of jointed rockmass, there are two types of regions around the intersection of borehole and joint in which the damage degree is… More >

Chunfang Yang^1,*, Jie Wang¹, Chengliang Lin¹, Huiqin Chen², Wenjuan Wang¹

CMC-Computers, Materials & Continua, Vol.60, No.2, pp. 633-644, 2019, DOI:10.32604/cmc.2019.06154

Abstract For the case of that only a single stego image of LSB (Least Significant Bit) matching steganography is available, the existing steganalysis algorithms cannot effectively locate the modified pixels. Therefore, an algorithm is proposed to locate the modified pixels of LSB matching based on spatial and wavelet filter fusion. Firstly, the validity of using the residuals obtained by spatial and wavelet filtering to locate the modified pixels of LSB matching is analyzed. It is pointed out that both of these two kinds of residuals can be used to identify the modified pixels of LSB matching with success rate higher than… More >