• Title/Summary/Keyword: 나비어의 운동방정식

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Three-Dimensional Field Equations, Equations of Motion, and Energy Functionals for Thick Shells of Revolution with Arbitrary Curvature and Variable Thickness (임의의 곡률과 변두께를 갖는 두꺼운 축대칭 회전 셸의 3차원적 장방정식, 운동 방정식, 에너지 범함수)

  • 강재훈;이은택;양근혁
    • Journal of KSNVE
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    • v.11 no.1
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    • pp.156-166
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    • 2001
  • This work uses tensor calculus to derive a complete set of three-dimensional field equations well-suited for determining the behavior of thick shells of revolution having arbitrary curvature and variable thickness. The material is assumed to be homogeneous, isotropic and linearly elastic. The equations are expressed in terms of coordinates tangent and normal to the shell middle surface. The relationships are combined to yield equations of motion in terms of orthogonal displacement components taken in the meridional, normal and circumferential directions. Strain energy and kinetic energy functionals are also presented. The equations of motion and energy functionals may be used to determine the static or dynamic displacements and stresses in shells of revolution, including free and forced vibration and wave propagation.

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IMPROVEMENT OF MPS METHOD IN SIMULATING VIOLENT FREE-SURFACE MOTION AND PREDICTING IMPACT-LOADS (유체 충격 하중 예측을 위한 MPS법의 개량)

  • Hwang, S.C.;Lee, B.H.;Park, J.C.
    • Journal of computational fluids engineering
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    • v.15 no.1
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    • pp.71-80
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    • 2010
  • The violent free-surface motions and the corresponding impact loads are numerically simulated by using the Moving Particle Semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka (1996) for incompressible flows. In the original MPS method, there were several shortcoming including non-optimal source term, gradient and collision models, and search of free-surface particles, which led to less-accurate fluid motions and non-physical pressure fluctuations. In the present study, how those defects can be remedied is illustrated by step-by-step improvements in respective processes of the revised MPS method. The improvement of each step is explained and numerically demonstrated. The numerical results are also compared with the experimental results of Martin and Moyce (1952) for dam-breaking problem. The current numerical results for violent free-surface motions and impact pressures are in good agreement with their experimental data.

Fluid Simulations in Academy Awarded Movies (아카데미상 영화에서 유체 시뮬레이션 기술)

  • Kim, Myung-Gyu;Oh, Seung-Taik;Choi, Byoung-Tae
    • Journal of the Korea Computer Graphics Society
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    • v.14 no.3
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    • pp.19-30
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    • 2008
  • Fluid simulation for computer graphics is a field of generating the realistic movements of water, smoke, fire, explosion, sand and related phenomena to be used in motion pictures and video games. In this paper we review the fluid simulation technologies and present a trend analysis for the simulation methods used in the recent movies. First of all, for this purpose, the two methods that are most widely used for fluid simulation are explained as well as their technical issues. These two methods are classified into Eulerian grid-based and Lagrangian particle-based approaches. Next, focusing on the achievements of the scientists and engineers that the 2008 Sci-Tech Oscar Awards are given to, the features of their fluid simulation technologies are analyzed. Finally, we anticipate that there are and will be the needs for visualizing fluid interaction with rigid and soft bodies and topological change among solid, fluid and gas, creating digital creatures based on fluid simulation and presenting interaction between creature and fluid.

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