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  • Open Access


    A Hydrodynamic Assessment of a Remotely Operated Underwater Vehicle Based on Computational Fluid Dynamic – Part 1 – Numerical Simulation

    Christian Boe, Jose Rodriguez, Carlos Plazaola, Ilka Banfield A maly Fong, Rony Caballero, Adan Vega

    CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.2, pp. 165-177, 2013, DOI:10.3970/cmes.2013.090.165

    Abstract The authors have developed a remote operate vehicle (ROV) that allow carried out highly risky task, in confined space such as inside of submerged sewers and pipes systems, areas were commercial ROV may not provide good performing. In addition, this ROV is low cost. This paper analyses based on the computational fluid dynamic the hydrodynamic performance of this ROV. The first part of the paper presents the theoretical approach and introduces the finite volume model developed in order to complete the study. Results of the model compare with published research shows good agreement. The second (forthcoming) part of the paper… More >

  • Open Access


    Numerical Modelling of Turbulence Effects on Droplet Collision Dynamics using the Level Set Method

    Ashraf Balabel1,

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 283-301, 2012, DOI:10.3970/cmes.2012.089.283

    Abstract This paper presents a novel numerical method for solving the twophase flow problems with moving interfaces in either laminar or turbulent flow regimes. The developed numerical method is based on the solution of the Reynolds- Averaged Navier Stokes equations in both phases separately with appropriate boundary conditions located at the interface separating the two fluids. The solution algorithm is performed on a regular and structured two-dimensional computational grid using the control volume approach. The complex shapes as well as the geometrical quantities of the interface are determined via the level set method. The numerical method is firstly validated against the… More >

  • Open Access


    On the Use of PEBI Grids in the Numerical Simulations of Two-Phase Flows in Fractured Horizontal Wells

    Yongsheng An1, Xiaodong Wu1, Deli Gao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 123-142, 2012, DOI:10.3970/cmes.2012.089.123

    Abstract The accuracy of numerical simulation of a two-phase (oil and water) flow in a fractured horizontal well depends greatly upon the types of grids used in the computation. Cartesian grids have been widely used in recent years, but they have some disadvantages in describing complex structural wells, such as fractured horizontal wells. For example, Cartesian grids are not efficient in describing the main wellbores and the fractures of fractured horizontal wells, and the results can frequently suffer from grid orientation effects, even though a grid-refinement is often introduced to enhance the adaptability of a Cartesian grid. The PEBI (Perpendicular Bisector)… More >

  • Open Access


    Mechanical Analyses of Casings in Boreholes, under Non-uniform Remote Crustal Stress Fields: Analytical & Numerical Methods

    Fei Yin1, Deli Gao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.1, pp. 25-38, 2012, DOI:10.3970/cmes.2012.089.025

    Abstract The methods to design the casings used in oilfields, are currently based on the assumptions that the remote crustal-stress-field is axially symmetric, in plane strain. However, most of the failures of the casings are caused by non-uniform and asymmetric far-field crustal stresses, so that it is necessary for a proper design of the casings, to investigate and understand the casing's behavior under non-uniform far-field crustal stresses. A mechanical model is first established for the system, consisting of the casing and formation, by using the plane strain theory of linear elasticity. The non-uniform crustal stress is resolved into a uniform stress… More >

  • Open Access


    Natural Convection Flow and Heat Transfer in Square Enclosure Asymetrically Heated from Below: A Lattice Boltzmann Comprehensive Study

    Taoufik Naffouti1,2 and Ridha Djebali1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.3, pp. 211-228, 2012, DOI:10.3970/cmes.2012.088.211

    Abstract This paper reports numerical results of natural convection flow evolving inside confined medium defined by two-dimensional square enclosure containing isothermal hot source placed asymmetrically at bottom wall. The sides-walls are isothermally cooled at a constant temperature; however the ceiling and the rest of bottom wall are insulated. The lattice Boltzmann method is used to solve the dimensionless governing equations with the associated boundary conditions. The flow is monitored by the Grashof number and the Prandtl number taken here 0.71. Numerical simulations are performed to study the effects of Grashof number ranging from 104 to 106, hot source length from 0.1… More >

  • Open Access


    Numerical Simulation of Plane Crack Using Hermite Cubic Spline Wavelet

    Jiawei Xiang1,2, Yanxue Wang3, Zhansi Jiang3, Jiangqi, Long1, Guang Ma1

    CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.1, pp. 1-16, 2012, DOI:10.3970/cmes.2012.088.001

    Abstract Two-dimensional wavelet-based numerical approximation using Hermite cubic spline wavelet on the interval (HCSWI) is proposed to solve stress intensity factors (SIFs) of plate structures. The good localization property of wavelets is used to approximate displacement fields by multi-scale bases of HCSWI. Example computations are performed for plates with a central crack and double edge cracks. The numerical results prove that, compared with the conventional finite element method and the analytical solutions, the new procedure are efficient in both its accuracy and its reduction of degree of freedoms (DOFs). More >

  • Open Access


    Numerical Simulation of Gas-assisted Injection Molding Process for A Door Handle

    Qiang Li, Jie Ouyang1, Xuejuan Li2, Guorong Wu2, Binxin Yang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 247-268, 2011, DOI:10.3970/cmes.2011.074.247

    Abstract A unified mathematical model is proposed to predict the short shot, primary and secondary gas penetration phenomenon in gas-assisted injection molding (GAIM) process, where the Cross-WLF model and two-domain modified Tait equation are employed to simulate the melt viscosity and density in the whole process, respectively. The governing equations of two-phase flows including gas, air and polymer melt are solved using finite volume method with SIMPLEC technology. At first, two kinds of U-shaped gas channels are modeled, where the shape corner and generous corner cases are studied. At last, as a case study, the short shot, primary and secondary gas… More >

  • Open Access


    Numerical Simulation of Graphite Properties Using X-ray Tomography and Fast Multipole Boundary Element Method

    H. T. Wang, G. Hall, S. Y. Yu, Z. H. Yao

    CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 153-174, 2008, DOI:10.3970/cmes.2008.037.153

    Abstract Graphite materials are widely used in gas-cooled nuclear reactors as both moderators and reflectors. The graphite properties change when the microstructure damage occurs due to the in-core radiation and oxidation, thereby having a strong impact on the service life of graphite. In this paper, the X-ray tomography and the boundary element method (BEM) are introduced to the microstructure modeling and numerical simulations of both the mechanical and thermal property changes of nuclear graphite due to radiolytic oxidation. The model is established by the three-dimensional X-ray scan on the isotropic nuclear graphite Gilsocarbon, which is used in the UK commercial reactors.… More >

  • Open Access


    ADVENTURE AutoGL: A Handy Graphics and GUI Library for Researchers and Developers of Numerical Simulations

    H. Kawai1

    CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.3, pp. 111-120, 2006, DOI:10.3970/cmes.2006.011.111

    Abstract ADVENTURE AutoGL (pronounced as ‘Ote- ga-lu’) is a graphics and GUI library, dedicated for simulation-based research and development. It is designed for the simulation users to develop their own data viewers and editors. Currently, the library is used among many researchers and simulation users, mainly in universities and national research centers. Its functionalities and supported platforms are explained. AutoGL applications of various kinds of simulation methods are demonstrated also. More >

  • Open Access


    Numerical study on seepage property of karst collapse columns under particle migration

    Banghua Yao1,2, Jianping Wei1, Dengke Wang1, Dan Ma2,3, Zhanqing Chen2

    CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 81-100, 2013, DOI:10.3970/cmes.2013.091.081

    Abstract Presently, there is an increasing number of water outburst accidents in China as mining activity continues to develop to deeper ground. In these accidents, water outburst caused by karst collapse columns often results in serious damage, involving both the loss of lives and significant economic loss. Therefore, it is of utmost importance to study the seepage property and water outburst mechanism of karst collapse columns. In this paper, based on the seepage theory and the groundwater dynamic theory of porous media, a fluid-solid coupling model for karst collapse columns was built and then imported into COMSOL Multiphysics to be solved,… More >

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