Home / Advanced Search

  • Title/Keywords

  • Author/Affliations

  • Journal

  • Article Type

  • Start Year

  • End Year

Update SearchingClear
  • Articles
  • Online
Search Results (262)
  • Open Access

    ARTICLE

    Strain Energy on the Surface of an Anisotropic Half-Space Substrate: Effect of Quantum-Dot Shape and Depth

    E. Pan1,2, Y. Zhang2, P. W. Chung3, M. Denda4

    CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 157-168, 2008, DOI:10.3970/cmes.2008.024.157

    Abstract Quantum-dot (QD) semiconductor synthesis is one of the most actively investigated fields in strain energy band engineering. The induced strain fields influence ordering and alignment, and the subsequent surface formations determine the energy bandgap of the device. The effect of the strains on the surface formations is computationally expensive to simulate, thus analytical solutions to the QD-induced strain fields are very appealing and useful. In this paper we present an analytical method for calculating the QD-induced elastic field in anisotropic half-space semiconductor substrates. The QD is assumed to be of any polyhedral shape, and its surface is approximated efficiently by… More >

  • Open Access

    ARTICLE

    Acoustic Scattering from Fluid Bodies of Arbitrary Shape

    B. Ch,rasekhar1, Sadasiva M. Rao2

    CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.1, pp. 67-80, 2007, DOI:10.3970/cmes.2007.021.067

    Abstract In this work, a simple and robust numerical method to calculate the scattered acoustic fields from fluid bodies of arbitrary shape subjected to a plane wave incidence is presented. Three formulations are investigated in this work$viz.$ the single layer formulation (SLF), the double layer formulation (DLF), and the combined layer formulation (CLF). Although the SLF and the DLF are prone to non-uniqueness at certain discrete frequencies of the incident wave, the CLF is problem-free, eliminates numerical artifacts, and provides a unique solution at all frequencies. Further, all the three formulations are surface formulations which implies that only the scatterer surface… More >

  • Open Access

    ARTICLE

    An Unconditionally Time-Stable Level Set Method and Its Application to Shape and Topology Optimization

    S.Y. Wang1,2, K.M. Lim2,3, B.C. Khoo2,3, M.Y. Wang4

    CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.1, pp. 1-40, 2007, DOI:10.3970/cmes.2007.021.001

    Abstract The level set method is a numerical technique for simulating moving interfaces. In this paper, an unconditionally BIBO (Bounded-Input-Bounded-Output) time-stable consistent meshfree level set method is proposed and applied as a more effective approach to simultaneous shape and topology optimization. In the present level set method, the meshfree infinitely smooth inverse multiquadric Radial Basis Functions (RBFs) are employed to discretize the implicit level set function. A high level of smoothness of the level set function and accuracy of the solution to the Hamilton-Jacobi partial differential equation (PDE) can be achieved. The resulting dynamic system of coupled Ordinary Differential Equations (ODEs)… More >

  • Open Access

    ARTICLE

    Weight Function Shape Parameter Optimization in Meshless Methods for Non-uniform Grids

    J. Perko1, B. Šarler2

    CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.1, pp. 55-68, 2007, DOI:10.3970/cmes.2007.019.055

    Abstract This work introduces a procedure for automated determination of weight function free parameters in moving least squares (MLS) based meshless methods for non-uniform grids. The meshless method used in present work is Diffuse Approximate Method (DAM). The DAM is structured in 2D with the one or two parameter Gaussian weigh function, 6 polynomial basis and 9 noded domain of influence. The procedure consists of three main elements. The first is definition of the reference quality function which measures the difference between the MLS approximation on non-uniform and hypothetic uniform node arrangements. The second is the construction of the object function… More >

  • Open Access

    ARTICLE

    A Geometric Deformation Constrained Level Set Method for Structural Shape and Topology Optimization

    S.Y. Wang1,2, K.M. Lim2,3, B.C. Khoo2,3, M.Y. Wang4

    CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.3, pp. 155-182, 2007, DOI:10.3970/cmes.2007.018.155

    Abstract In this paper, a geometric deformation constrained level set method is presented as an effective approach for structural shape and topology optimization. A level set method is used to capture the motion of the free boundary of a structure. Furthermore, the geometric deformation of the free boundary is constrained to preserve the structural connectivity and/or topology during the level set evolution. An image-processing-based structural connectivity and topology preserving approach is proposed. A connected components labeling technique based on the 4-neighborhood connectivity measure and a binary image is used for the present region identification. The corresponding binary image after an exploratory… More >

  • Open Access

    ARTICLE

    Acoustic Scattering from Complex Shaped Three Dimensional Structures

    B. Chrasekhar1, S. M. Rao2

    CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.2, pp. 105-118, 2005, DOI:10.3970/cmes.2005.008.105

    Abstract In this work, a simple, robust, and an efficient numerical algorithm to calculate the scattered acoustic fields from complex shaped objects such as aircrafts and missiles, subjected to a plane wave incidence is presented. The work is based on the recently proposed method of moments (MoM) and the potential theory, unlike the standard Helmholtz integral equation (HIE) solution method. For the numerical solution, the scattering structure is approximated by planar triangular patches. For the MoM solution of complex bodies involving open/closed/intersecting surfaces, a unified set of basis functions to approximate the source distribution is defined. These basis functions along with… More >

  • Open Access

    ARTICLE

    PDE-Driven Level Sets, Shape Sensitivity and Curvature Flow for Structural Topology Optimization

    Michael Yu Wang1, Xiaoming Wang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 373-396, 2004, DOI:10.3970/cmes.2004.006.373

    Abstract This paper addresses the problem of structural shape and topology optimization. A level set method is adopted as an alternative approach to the popular homogenization based methods. The paper focuses on four areas of discussion: (1) The level-set model of the structure’s shape is characterized as a region and global representation; the shape boundary is embedded in a higher-dimensional scalar function as its “iso-surface.” Changes of the shape and topology are governed by a partial differential equation (PDE). (2) The velocity vector of the Hamilton-Jacobi PDE is shown to be naturally related to the shape derivative from the classical shape… More >

  • Open Access

    ARTICLE

    Shape Optimization of Elastic Structural Systems Undergoing Large Rotations: Simultaneous Solution Procedure

    Adnan Ibrahimbegovic1, Catherine Knopf-Lenoir2

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.2, pp. 337-344, 2003, DOI:10.3970/cmes.2003.004.337

    Abstract In this work we present an unconventional procedure for combining the optimal shape design and nonlinear analysis in mechanics. The main goal of the presented procedure is to enhance computational efficiency for nonlinear problems with respect to the conventional, sequential approach by solving the analysis and design phases simultaneously. A detailed development is presented for the chosen model problem, the 3d rod undergoing large rotations. More >

  • Open Access

    ARTICLE

    Shape Optimization of Body Located in Incompressible Navier--Stokes Flow Based on Optimal Control Theory

    H. Okumura1, M. Kawahara1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 71-78, 2000, DOI:10.3970/cmes.2000.001.231

    Abstract This paper presents a new approach to a shape optimization problem of a body located in the unsteady incompressible viscous flow field based on an optimal control theory. The optimal state is defined by the reduction of drag and lift forces subjected to the body. The state equation used is the transient incompressible Navier--Stokes equations. The shape optimization problem can be formulated to find out geometrical coordinates of the body to minimize the performance function that is defined to evaluate forces subjected to the body. The fractional step method with the implicit temporal integration and the balancing tensor diffusivity (BTD)… More >

  • Open Access

    ARTICLE

    Thermal Behavior of a U-shaped Channel Subject to a Convective Air Jet and Immersed in an Isothermal Medium

    Meryem NAOUM1, Mustapha EL ALAMI2

    FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.2, pp. 56-68, 2016, DOI:10.3970/fdmp.2016.012.056

    Abstract A numerical study of mixed convection from a U-shaped channel is carried out. The flow is considered two dimensionnel. The inlet opening is adjusted in the right vertical part of the channel, while the outlet one is placed on the left vertical part. Navier–Stokes equations are solved using a control volume method and the SIMPLEC algorithm is considered for the treatment of pressure–velocity coupling. Special emphasis is given to detail the effect of the Reynolds and Rayleigh numbers on the heat transfer generated by mixed convection. The results are given for the parameters of control as, Rayleigh number (5.103≤Ra≤107), Prandtl… More >

Displaying 231-240 on page 24 of 262. Per Page