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  • Open Access

    ARTICLE

    Numerical Simulations for Coupled Pair of Diffusion Equations by MLPG Method

    S. Abbasbandy1,2, V. Sladek3, A. Shirzadi1, J. Sladek3

    CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 15-38, 2011, DOI:10.3970/cmes.2011.071.015

    Abstract This paper deals with the development of a new method for solution of initial-boundary value problems governed by a couple of nonlinear diffusion equations occurring in the theory of self-organization in non-equilibrium systems. The time dependence is treated by linear interpolation using the finite difference method and the semi-discrete partial differential equations are considered in a weak sense by using the local integral equation method with approximating 2-d spatial variations of the field variables by the Moving Least Squares. The evaluation techniques are discussed and the applicability of the presented method is demonstrated on two illustrative examples with exact solutions… More >

  • Open Access

    ARTICLE

    Assessment of Pressure Waves Generated by Explosive Loading

    D. Kakogiannis1, D. Van Hemelrijck1, J. Wastiels1, S. Palanivelu2, W. Van Paepegem2, J. Vantomme3, A. Kotzakolios4, V. Kostopoulos4

    CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.1, pp. 75-94, 2010, DOI:10.3970/cmes.2010.065.075

    Abstract In the present study the estimation of the blast wave by two types of finite element methods is investigated: Eulerian multi-material modeling and pure Lagrangian. The main goal is to compare and study their ability to predict the clearing effect during blast. Element shape and improvements on the codes are also considered. For the Lagrangian finite element models the load is applied by using an empirical method, deriving from databases, for the time-spatial distribution of the pressure profiles. In the ideal case of the above method the blast load is applied as an equivalent triangular pulse to represent the decay… More >

  • Open Access

    ARTICLE

    Numerical Simulation of Fluid Induced Vibration of Graphenes at Micron Scales

    Y. Inoue1, R. Kobayashi1, S. Ogata1, T. Gotoh1

    CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 137-162, 2010, DOI:10.3970/cmes.2010.063.137

    Abstract Vibration of a single graphene and a pair of graphenes at micro meter scale induced by air flow is numerically simulated and examined by using a hybrid computational method starting from a microscopic level of description for the graphene. In order to bridge a huge gap in spatial and time scales in their motions, the carbon atoms of the graphene are represented by a small number of coarse grained particles, the fluid motion is described by the lattice Boltzmann equation and the momentum exchange at the boundary is treated by the time averaged immersed boundary method. It is found that… More >

  • Open Access

    ARTICLE

    A new incompressible Navier-Stokes solver combining Fourier pseudo-spectral and immersed boundary methods

    F.P. Mariano1, L.Q. Moreira1, A. Silveira-Neto1, C.B. da Silva2, J.C.F. Pereira2

    CMES-Computer Modeling in Engineering & Sciences, Vol.59, No.2, pp. 181-216, 2010, DOI:10.3970/cmes.2010.059.181

    Abstract A new numerical methodology combining Fourier pseudo-spectral and immersed boundary methods - IMERSPEC - is developed for fluid flow problems governed by the incompressible Navier-Stokes equations. The numerical algorithm consists in a classical Fourier pseudo-spectral methodology using the collocation method where wall boundary conditions are modelled by using an immersed boundary method (IBM). The performance of that new methodology is exemplified in two-dimensional numerical simulations of Green-Taylor decaying vortex, lid-driven cavity and flow over a square cylinder. The convergence rate, the accuracy, the influence of the Reynolds number and the external domain size are analyzed. This new method combines some… More >

  • Open Access

    ARTICLE

    An Advanced Implicit Meshless Approach for the Non-linear Anomalous Subdiffusion Equation

    Y. T. Gu1, P. Zhuang2, F. Liu3

    CMES-Computer Modeling in Engineering & Sciences, Vol.56, No.3, pp. 303-334, 2010, DOI:10.3970/cmes.2010.056.303

    Abstract Recently, the numerical modelling and simulation for anomalous subdiffusion equation (ASDE), which is a type of fractional partial differential equation(FPDE) and has been found with widely applications in modern engineering and sciences, are attracting more and more attentions. The current dominant numerical method for modelling ASDE is Finite Difference Method (FDM), which is based on a pre-defined grid leading to inherited issues or shortcomings. This paper aims to develop an implicit meshless approach based on the radial basis functions (RBF) for numerical simulation of the non-linear ASDE. The discrete system of equations is obtained by using the meshless shape functions… More >

  • Open Access

    ARTICLE

    Numerical Simulations of Flows over a Pair of Cylinders at Different Arrangements using the Immersed Boundary Method

    A.R. da Silva1, A. Silveira-Neto2,3, D.A. Rade2,4, R.Francis4, E.A. Santos4

    CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 285-304, 2009, DOI:10.3970/cmes.2009.050.285

    Abstract In the context of computational fluid dynamics a numerical investigation of incompressible flow around fixed pairs of rigid circular cylinders was carried out. The two-dimensional filtered Navier-Stokes equations with the Smagorinsky sub-grid scale model were solved using a Cartesian non-uniform grid. The immersed Boundary Method with the Virtual Physical Model was used in order to model the presence of two circular cylinders embedded in the flow. The fractional time step method was used to couple pressure and velocity fields. The simulations were carried out for Reynolds number equal to 72,000 for pitch ratio equal to 2 and different arrangements regarding… More >

  • Open Access

    ARTICLE

    Numerical Simulation and Natural Computing applied to a Real World Traffic Optimization Case under Stress Conditions:

    M.J. Galán Moreno, J.J. Sánchez Medina, L. Álvarez Álvarez E. Rubio Royo1

    CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 191-226, 2009, DOI:10.3970/cmes.2009.050.191

    Abstract Urban traffic is a key factor for the development of a city. There exist many different approaches facing traffic optimization. In our case we have focused on traffic lights optimization. We have designed and tested a new architecture to optimize traffic light cycle times. The purpose of this research is to demonstrate the good performance of our architecture in a congested scenario. We have simulated several congestion situations for a very large real world traffic network - "La Almozara" in Zaragoza, Spain. Our results seem encouraging in this extreme situation. As we increase the load in the network we get… More >

  • Open Access

    ARTICLE

    MLPG_R Method for Numerical Simulation of 2D Breaking Waves

    Q.W. Ma1,2, J.T. Zhou1

    CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.3, pp. 277-304, 2009, DOI:10.3970/cmes.2009.043.277

    Abstract Following our previous work, the Meshless Local Petrov-Galerin me -thod based on Rankine source solution (MLPG_R) will be extended in this paper to deal with breaking waves. For this purpose, the governing equation for pressure is improved and a new technique called Mixed Particle Number Density and Auxiliary Function Method (MPAM) is suggested for identifying the free surface particles. Due to complexity of the problem, two dimensional (2D) breaking waves are only concerned here. Various cases are investigated and some numerical results are compared with experimental data available in literature to show the newly developed method is robust. More >

  • Open Access

    ARTICLE

    Numerical Modeling of Short-Pulse Laser Interactions with Multi-Layered Thin Metal Films

    E. Majchrzak1, B. Mochnacki2, A. L. Greer3, J. S. Suchy4

    CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.2, pp. 131-146, 2009, DOI:10.3970/cmes.2009.041.131

    Abstract Multi-layered thin metal film subjected to a short-pulse laser heating is considered. Mathematical description of the process discussed bases on the equation in which there appear the relaxation time and the thermalization time (dual-phase-lag-model). In this study we develop a three level implicit finite difference scheme for numerical modelling of heat transfer in non-homogeneous metal film. At the interfaces an ideal contact between successive layers is assumed. At the stage of computations a solution of only one three-diagonal linear system corresponds to transition from time t to t + Δt. The mathematical model, numerical algorithm and examples of computations are… More >

  • Open Access

    ARTICLE

    Simulation of high explosive explosion using adaptive material point method

    Shang Ma1, Xiong Zhang1,2, Yanping Lian1, Xu Zhou3

    CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 101-124, 2009, DOI:10.3970/cmes.2009.039.101

    Abstract Numerical simulation of high explosive explosion problems is a big challenge to traditional numerical methods because explosion usually involves extremely large deformation and multi-material interaction of different phases. Recently developed meshfree methods show much advantages over mesh-based method for problems associated with very large deformation. Some of them have been successfully applied to impact and explosion problems, such as smoothed particle hydrodynamics (SPH). Similar to SPH, material point method (MPM) is an efficient meshfree particle method solving continuum problems. With combination of the advantages of Eulerian and Lagrangian methods, MPM is a promising numerical tool for solving large deformation problems,… More >

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