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  • Title/Summary/Keyword: computational numerical analysis

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Numerical Analysis of the flow Characteristics in Intake-Port Piston Head Configurations in a Gasoline Direct-Injection Engine. (가솔린직접분사기관에서 흡기포트 및 피스톤의 형상에 따른 유동해석)

  • Park Chan-Guk;Park Hyung-Koo;Lim Myung-Taeck
    • Journal of computational fluids engineering
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    • v.4 no.3
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    • pp.21-27
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    • 1999
  • In this paper, tile characteristics of flow resulting from the configurations of piston head and intake-port of the cylinder in a gasoline-direct-injection engine are investigated numerically. Calculations are carried out from intake process to the end of compression. GTT code which includes the third order upwind Chakravarthy-Osher TVD scheme and κ-ε turbulence model with the law of wall as a boundary condition. As a result, a piston head with a smaller radius of curvature and larger radius gives stronger reverse tumble. It is also shown that as the maximum tumble ratio increases by the configuration of the intake-port the tumble ratio at the end of compression stroke increases. It is concluded that flows at the end of compression stroke can be controlled by the optimum design of intake-port and piston head.

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Computational analysis of coupled fluid-structure for a rotor blade in hover (정지 비행하는 로터 블레이드의 전산 유체-구조 결합 해석)

  • Kim, Hae-Dong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.12
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    • pp.1139-1145
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    • 2008
  • numerical study on the coupled fluid-structure for a rotor blade in hover was conducted. Computational fluid dynamics code with enhanced wake-capturing capability is coupled with a simple structural dynamics code based on Euler-Bernoulli's beam equation. The numerical results show a reasonable blade structural deformation and aerodynamic characteristics.

NUMERICAL ANALYSIS OF FLOW AROUND RECTANGULAR CYLINDERS WITH VARIOUS SIDE RATIOS

  • Rokugou Akira;Okajima Atsushi;Gutierrez Isaac
    • Journal of computational fluids engineering
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    • v.10 no.1
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    • pp.1-7
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    • 2005
  • Three-dimensional numerical analysis of the flow around rectangular cylinders with various side ratios, D/H, from 0.2 to 2.0, was carried out for Reynolds number of 10³ by using a multi-directional finite difference method on a regular-arranged multi-grid. The predicted results are in good agreement with the experimental data. It is found that fluid dynamic characteristics of rectangular cylinders alternate between the high-pressure mode and the low-pressure mode of the base pressure for D/H=0.2-0.6. We show that this phenomenon is induced by the change of the flow pattern around rectangular cylinders.

Elastic Critical Load of Non-symmetrically Tapered Columns by Numerical Method (수치해석법에 의한 비대칭 변단면 기둥의 탄성 임계하중)

  • 신세욱;김선혜;이수곤
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.04a
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    • pp.11-18
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    • 1999
  • For the proper design of a slender compression member, the exact determination of the elastic critical load is crucial, In the cases of non-prismatic compression members, the determinations of the elastic critical load cannot be usually expressed in closed forms. h this paper, the non-symmetrically tapered compression members with arbitrary boundary conditions me analysed by using the finite element method to determine the elastic critical load. The main parameters considered in the numerical analysis are the In Parameter, α and the sectional property parameter, m. To generaliza the unmerical analysis, of the computed results for each sectional parameter, m are presented in algebraic equations, which agrees fairy well with those by F.E.M in most cases.

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The Values of J-integral and Shapes of Plastic Zone Near a Crack Tip of Cracked Panels by the ρ-Version of F.E.M. (ρ-Version 유한요소법에 의한 균열판의 소성역 형상과 J-적분값 산정)

  • 홍종현;우광성
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.04a
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    • pp.42-49
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    • 1999
  • Because the linear elastic tincture analysis has been proved to be insufficient in predicting the failure of cracked bodies, in recent years, a number of fracture concepts have been studied which remain applicable in the presence of large-scale plasticity near a crack tip. This work thereby presents a new finite element model, as accurate as possible, to analyze plane problems of ductile fracture under large-scale yielding conditions. Based on the incremental theory of plasticity, the p-version finite element analysis is employed to account for the values of J-integral, the most dominant fracture parameter, and the shape of plastic zone near a crack tip by using the J-integral method and equivalent domain integral method. The numerical results by the proposed model are compared with the theoretical solutions in literatures and the numerical solutions by the i,-version of F.E.M.

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Natural Frequencies of Simply Supported Tapered Beams (단순지지 변단면보의 고유진동수 산정)

  • 안성기;김순철;이수곤
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.04a
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    • pp.137-144
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    • 1999
  • The finite element method was adopted to find out the natural frequencies of a sinusoidally tapered beam with simply supported boundary conditions. The parameters considered in the numerical analysis are the taper parameter, α (α=0.0, 0.1, ~ , 2.0) and the sectional property parameters, m and n [(m, n):(0, 2), (1, 3), (2, 4)]. It is generally known that the results of the numerical analysis corresponding to each pair of sectional property parameters, (m, n) are represented by second order polynominals of α . The coefficients of a in the polynominals are determined by using the regression technique, which reveals small m in most cases of given sectional property parameters (m, n).

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Numerical Analysis on Buckling of Longitudinal Bar in Reinforced Concrete Columns (철근콘크리트 기둥의 구조좌굴에 관한 수치해석)

  • 이리형;박재형;이용택
    • Computational Structural Engineering
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    • v.8 no.2
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    • pp.73-84
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    • 1995
  • The study summarized in this paper is concerned with the buckling of longitudinal bars in reinforced concrete columns with numerical analysis method. The objectives of this study are (1) to investigate the stress transfer mechanism between concrete and reinforcement and (2) to propose a modeling equation. The results give an acceptable agreement between the proposed modeling equation and published computer packages as follows; (1) the proposed equation is a possible of strain softening of concrete and buckling of reinforcement. (2) the buckling of longitudinal bar is mainly influenced by spacing of hoop and location of the bar

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A Study on Development of Numerical Analysis Method Behavior for Properties of Steel Structure Member and Frame (강구조 부재와 골조의 거동 성상에 대한 해석수법의 개발에 관한 연구)

  • 박정민;김화중;이상재
    • Computational Structural Engineering
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    • v.9 no.1
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    • pp.115-123
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    • 1996
  • This paper was developed to computer program, which is about to analyize nonlinear behavior of structural member and frame including to geometric and material nonlineality, and formulated to the relationship of stress-strain of steel. In order to examplity the efficiency of this program, the numerical analysis was done for H section steel beam and square steel tube column subjected to monotonic load, and braced steel frame subjected to repeated horizontal forces. The obtained results by this program were in accordance with existing experimental and analytical results respectively.

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A Numerical Analysis of High Speed Flow over Blunt Body Using Upwind Navier-Stokes Method (Upwind Navier-Stokes 방정식을 이용한 무딘 물체 주위의 유동장 해석)

  • Kwon C. O.;Kim S. D.;Song D. J.
    • Journal of computational fluids engineering
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    • v.1 no.1
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    • pp.123-141
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    • 1996
  • In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone(5°) geometry. The effective gamma(γ), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about 3 ∼ 5 percent. The heat transfer coefficient were also calculated. The results were compared with VSL results in order to validate the current numerical analysis. The results from current method were compared well VSL results ; however, not well at near nose. The proper boundary condition and grid system will be studied to improve the solution quality.

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Development of A Three-Dimensional Euler Solver for Analysis of Contraction Flow (수축부 유동 해석을 위한 삼차원 Euler 방정식 풀개 개발)

  • Kim J.;Kim H. T.
    • 한국전산유체공학회:학술대회논문집
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    • 1995.10a
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    • pp.175-181
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    • 1995
  • Three-Dimensional Euler equations are solved numerically for the analysis of contraction flows in wind or water tunnels. A second-order finite difference method is used for the spatial discretization on the nonstaggered grid system and the 4-stage Runge-Kutta scheme for the numerical integration in time. In order to speed up the convergence, the local time stepping and the implicit residual-averaging schemes are introduced. The pressure field is obtained by solving the pressure-Poisson equation with the Neumann boundary condition. For the evaluation of the present Euler solver, numerical computations are carried out for the various contraction geometries, one of which was adopted in the Large Cavitation Channel for the U.S. Navy. The comparison of the computational results with the available experimental data shows good agreements.

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