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Aluminium alloy profile transient extrusion simulation using finite volume method

Zhongguo Jixie Gongcheng/China Mechanical Engineering 2006年第SUPPL.期17卷 96-98页

作者： Lou, Shumei Zhao, Guoqun Wang, Rui Shandong University Jinan 250061 China

Numerical simulation model for unsteady aluminum profile extrusion processes is built using Euler mesh and finite volume method (FVM), and the related key technologies are studied. Velocity and pressure fields are obtained iteratively by simple algorithm. Temperature and equivalent strain rate fields calculated according to velocity field are used to update the dynamic viscosity coefficient associated with the constitutive equations for hot extrusion of aluminum profile. VOF (volume of fluid) method is included to trace material flow front. The 'moving grids system' is introduced to treat boundaries moving problem of the calculated area caused by the moving extrusion ram. The auto-adjustment of the time increment is realized to ensure the stability and efficiency of the simulation. The program was developed, typical extrusion processes were simulated, and the exactness of the FVM model built in the program is proved.

关键词： Euler mesh Finite volume method (FVM) simple algorithm VOF method

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Solution of transport equations on unstructured meshes with cell-centered colocated variables. Part I: Discretization

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2005年第6期48卷 1117-1127页

作者： Date, AW Indian Inst Technol Dept Mech Engn Bombay 400076 Maharashtra India

This paper describes discretization of transport equations on unstructured meshes with cell-centered colocated variables. The problem of zig-zag pressure prediction is eliminated by introducing smoothing pressure correction derived by Date [A.W. Date, Complete pressure correction algorithm for solution of incompressible Navier-Stokes equations on a non-staggered grid, Numer. Heat Transfer, Part B 29 (1995) 441-458]. The finite-volume discretization is carried out in a structured grid like manner by invoking a special line-structure to evaluate convective-diffusive transport across the cell-faces. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： simple algorithm smoothing pressure correction unstructured meshes colocated variables line-structure

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Two correlation patterns as indicators for underlying dynamics of complex systems

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Physical Review E 2005年第1期71卷 017103-017103页

作者： Yuanfang Wu Lianshou Liu Yingdan Wang Yuting Bai Hongbo Liao Institute of Particle Physics Hua-Zhong Normal University Wuhan 430070 China

Two spatial correlation patterns, fixed-to-arbitrary and neighboring bin correlation patterns, are suggested. It is demonstrated that these patterns present scale-independent and distinguishable measures for correlated and uncorrelated random multiplicative cascade processes. Their application to very high multiplicity events in relativistic heavy ion collisions is discussed.

关键词： FULLY-DEVELOPED TURBULENCE MULTIPARTICLE PRODUCTION simple algorithm IDENTICAL PIONS SCALING LAWS HIGH-ENERGY QCD JETS MULTIPLICITY COLLISIONS MODEL

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A LEVEL SET METHOD FOR SIMULATION OF RISING BUBBLE

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Journal of Hydrodynamics 2004年第4期16卷 379-385页

作者： HUANGJun-tao ZHANGHui-sheng DepartmentofMechanicsandEngineeringSciences FudanUniversityShanghai200433China

A level set method, the TVD scheme of second-order upwind procedure coupledwith flux-limiter, and simple algorithm were incorporated to simulate the flow and interfacialmotion of immiscible two-fluids with large density ratio and viscosity ratios, large topologydistortion and surface tension. As a numerical example axi-symmetric rising bubbles wereinvestigated. It is found that the method is numerically stable and has good convergence propertyand the results are in good agreement with other works.

关键词： level set method high-resolution scheme simple algorithm rising bubble

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Three dimensional, two phase flow mathematical model for PEM fuel cell: Part I. Model development

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ENERGY CONVERSION AND MANAGEMENT 2004年第11-12期45卷 1861-1882页

作者： Hu, MR Gu, AZ Wang, MH Zhu, XJ Yu, LJ Shanghai Jiao Tong Univ Inst Refrigerat & Cryogen Shanghai 200030 Peoples R China Shanghai Jiao Tong Univ Inst Fuel Cell Shanghai 200030 Peoples R China Shanghai Jiao Tong Univ Sch Mech Engn Dept Energy Shanghai 200240 Peoples R China

A full three dimensional PEM fuel cell model is developed, which considers not only the rib resistance to the species but both the single and two phase flow and transport in the gas channels and diffusers at both the anode and cathode sides of the PEM fuel cell. Two sets of boundary conditions, one for a conventional flow field and the other for an interdigitated one, are presented. A detailed discussion of the numerical techniques for the PEM fuel cell model is given with a flow diagram to provide an overview of the solution procedure using the FORTRAN language. A rigorous validation method is used to show good agreement between our predicted results and the experimental data. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： PEM fuel cell two phase flow model conventional flow field interdigitated flow field simple algorithm

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A study on preconditioning iterative methods and relativity of pressure in the numerical calculation of fluid flow

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NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS 2004年第5期20卷 789-802页

作者： Hirano, H Yoshida, H Ozoe, H Okamoto, N Okayama Univ Sci Dept Appl Chem Okayama 7000005 Japan Hiroshima Univ Dept Chem Engn Higashihiroshima 7398527 Japan Kyushu Univ Inst Mat Chem & Engn Kasuga Fukuoka 8168580 Japan

This article presents the effect of preconditioning iterative methods on boundary conditions of the pressure-correction in the numerical computation of fluid flow with known velocity components on all boundaries using the simple algorithm. In such computation, a set of solutions of the pressure-correction is indefinite, because only the Neumann condition is imposed on all boundaries. However, solutions become unique if the value of pressure-correction is fixed at least on one boundary point, and the Dirichlet condition is additionally imposed. Though both conditions must give exactly the same velocity and temperature fields, this problem arises from the relativity of the pressure. The mathematical illustration for this problem is provided using the numerical computation of the natural convection in an enclosure. It is concluded that the preconditioner adopted and the condition that only the Neumann condition on all boundaries is given are effective to reduce the number of iterations in solving the linear system of equations of the pressure-correction at the computation of the natural convection. (C) 2004 Wiley Periodicals, Inc.

关键词： Neumann condition Dirichlet condition relativity of pressure simple algorithm

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Control volume method for the thermal convection problem in a rotating spherical shell: Test on the benchmark solution

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STUDIA GEOPHYSICA ET GEODAETICA 2004年第4期48卷 741-746页

作者： Hejda, P Reshetnyak, M Acad Sci Czech Republ Inst Geophys CR-14131 Prague Czech Republic Russian Acad Sci Inst Phys Earth Moscow 123995 Russia Moscow MV Lomonosov State Univ Ctr Res Comp Moscow 119899 Russia

The development of the control volume method for the thermal convection problem in a rotating spherical shell is presented. In contrast to the spectral methods, commonly used in geodynamo simulations, the control volume method belongs to the class of grid methods (the solution is approximated by a set of discrete values in physical space). In the present paper we concentrate on some problems of convergence and stability of the method. Case 0 of the numerical dynamo benchmark (Christensen et al., 2001, Phys. Earth Planet. Inter., 128, 25-34) was used to check the correctness of our computer code. The results demonstrate good convergence to the suggested standard solution.

关键词： liquid core dynamo benchmark finite volume method simple algorithm

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Fluid dynamical view of pressure checkerboarding problem and smoothing pressure correction on meshes with colocated variables

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2003年第25期46卷 4885-4898页

作者： Date, AW Indian Inst Technol Dept Mech Engn Bombay 400076 Maharashtra India

This paper presents derivation of the pressure correction equation appropriate for colocated grids within the framework of the simple algorithm. It is shown that checkerboard prediction of pressure can be prevented by employing algebraic smoothing pressure correction [Numer. Heat Transfer, Part B 29 (1996) 441] that is very simple to implement on both the structured as well as unstructured grids. The ability of the smoothing correction (which is shown to be independent of transformations of the system of coordinates) in providing the necessary dissipation is explained and the connection of the former with requirements of the Stokes's laws is established. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： simple algorithm smoothing pressure correction structured and unstructured meshes colocated variables Navier-Stokes equations

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A real-time predictor-corrector interpolator for CNC machining

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JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME 2003年第3期125卷 449-460页

作者： Tsai, MC Cheng, CW Natl Cheng Kung Univ Dept Mech Engn Tainan 701 Taiwan

This paper presents a predictor-corrector interpolator (PCI) for the CNC machining of parts with parametric curves or surfaces. In contrast to existing parametric interpolators, the proposed method uses a simple algorithm as a predictor and the current feedrate command feedback compensation scheme as the corrector. The predictor adjusts itself according to the current feedrate command feedback, it also has the capability of predicting the next reference point of the parametric curves from the current reference point. As a result, the deviations between the current and desired feedrate commands will always fall within the specified feedrate command tolerances. This study aims at developing the mathematical analysis of the PCI, where the convergence condition is derived for the corrector In this present approach, the user can specify either constant or variable federate and also its feedrate command accuracy. Both the simulation and experiment results are presented to demonstrate the feasibility of the proposed PCI for machining the parametric curves represented in the Non-Uniform Rational B-Spline (NURBS) form.

关键词： .segments CNC machine parametric curves simple algorithm interpolators Predictor-Corrector CNC Machining existing parametric current feedrate command feedrate commands convergence condition NURBS form

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Space-like jet calculus for single gluon radiating processes

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PROGRESS OF THEORETICAL PHYSICS 2003年第6期109卷 981-993页

作者： Tanaka, H Sugiura, T Munehisa, T Kato, K Rikkyo Univ Dept Phys Tokyo 1718501 Japan Yamanashi Univ Fac Engn Kofu Yamanashi 4008511 Japan Kogakuin Univ Fac Gen Educ Tokyo 16386577 Japan

Three-body decay functions in space-like parton branching for a single gluon radiation accompanied by a quark (or an anti-quark) are calculated using jet calculus. Explicit expressions of the calculated results are presented. Some properties of the three-body decay functions for soft gluon radiation are also examined. It is pointed out that the three-body decay function for a quark in an initial state that decays into a gluon with a space-like virtuality gives a large positive contribution whose singularity is not absorbed by the angular ordering condition imposed on the two-body branching process.

关键词： Resolving qcd jets Leading order Parton showers Decay probabilities Perturbative qcd simple algorithm Simulation Coherence Interference Inclusion Perturbative QCD coherence Educated at mainstream school Quarks DECAY FUNCTION interference gluons space-like simulating

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