• Title/Summary/Keyword: 유한체적법

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Double-Diffusive Convection in Molten Pb-Sn Alloy (용융상태인 납-주석 합금의 이중확산유동)

  • ;Bergman, T. L.
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.2
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    • pp.27-35
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    • 1995
  • 액체 상태인 Pb-Sn 합금에 의한 이중확산유동에 대해 체비세프 콜로케이션 기법을 이용하여 수치해석하였다. 온도차에 의한 부력과 농도차에 의한 부력이 작을때에는 유동형태가 서서히 준정상상태에 이르러 아무런 진동현상을 볼 수 없다. 부력이 증가함에 따라 유동은 수직 농도 경계층을 파괴하여 플륨(Plume)형태의 유동을 생성시키고, 이는 시스템 내부로 성장한 후 소멸된다. 이러한 현상이 반복되면서 높은 주파수의 진동현상을 관찰할 수 있다.

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Viscous Flow Analysis of the Waterjet Duct (물분사 추진기 관내 점성유동해석)

  • 왕정용;전호환;박일룡;차상명
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.68-72
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    • 2000
  • In the present paper, the numerical calculations for the viscous duct flow of water jet propulsion systems ship are carried out. The governing equation, incompressible Navier-Stokes equation, is discretized and analysed by a Method with the stcandard turbulence modeling. For the calculations the duct flow which h e intake flows disturbed by the ship, the results dcuhted by the potenti used Numerical results show fairly good agreement with the experimental data

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Development of Incompressible flow solver based on unstructured FVM (비정렬 유한체적법을 이용한 비압축성 유동해석 코드 개발)

  • Kim Jong-Tae;Kim Yong-Mo;Maeng Joo-Sung
    • 한국전산유체공학회:학술대회논문집
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    • 1996.05a
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    • pp.33-39
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    • 1996
  • An incompressible flow stover based on the unstructured finite volume method has been developed. The flow domain is discretized by triangles in 2D or tetrahedra in 3D. The convective and viscous fluxes are obtained using edge connectivities of the unstructured meshes. The pressure-velocity coupling is handled by the artificial compressibility algorithm due to its computational efficiency associated with the hyperbolic nature of the resulting equations. Laminar test flow problems are computed and presented with a comparison against other numerical solutions or experimental results.

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Investigation of the Radiative Heating from Aircraft Plume with Particles (입자에 의한 항공기 플룸의 열복사 가열에 관한 연구)

  • Go, Gun-Yung;Yi, Kyung-Joo;Lee, Sung-Nam;Kim, Won-Cheol;Baek, Seung-Wook;Kim, Man-Young
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.9
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    • pp.737-744
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    • 2012
  • The finite volume method for radiation is applied for the analysis of radiative base heating by SE and PE of the aircraft exhaust plume. The exhaust plume is considered as an absorbing, emitting, and scattering medium, while the base plane is assumed to be cold and black. The radiative properties of non-gray gases are obtained through the WSGGM, and the particle is modelled as spheres. The present method is validated by comparing the results with those of the backward Monte-Carlo method and then the radiative base heating characteristics are analyzed by changing such various parameters as particle concentration, temperature, and scattering phase function. The results show that the radiative heat flux coming into the base plane decreases with altitude and distance, but it increases as the particle temperature increases. The forward scattering of particles increases PE while it decreases SE.

Calculation of overtopping discharge with time-dependent aspects of an embankment failure (시간에 따른 제방붕괴 양상을 고려한 월류량 산정)

  • Kim, Hyung-Jun;Kim, Jong-Ho;Jang, Won-Jae;Cho, Yong-Sik
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.3
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    • pp.69-78
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    • 2007
  • In this study, a time-dependent aspect of an embankment failure is considered to simulate a flood inundation map and calculate overtopping discharge induced by an embankment failure. A numerical model has been developed by solving the two dimensional nonlinear shallow water equations with a finite volume method on unstructured grids. To analyze a Riemann problem, the HLLC approximate Riemann solver and the Weighted Averaged Flux method are employed by using a TVD limiter and the source term treatment is also employed by using the operator splitting method. Firstly, the numerical model is applied to a dam break problem and a sloping seawall. Obtained numerical results show good agreements with experimental data. Secondly, the model is applied to a flow induced by an embankment failure by assuming that the width and elevation of embankment are varied with time-dependent functions. As a result of the comparison with each numerical overtopping discharge, established flood inundation discharges in the previous studies are overestimated than the result of the present numerical model.

Inverse Radiation Analysis of a Two-Dimensional Irregular Geometry Using Unstructured Triangular Meshes (비정렬 삼각 격자를 이용한 2 차원 비직교 형상에서의 역복사 해석)

  • Yi, Kyung-Joo;Baek, Seung-Wook;Kim, Man-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.6
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    • pp.561-567
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    • 2011
  • The inverse radiation analysis of a two-dimensional irregular configuration using unstructured triangular meshes is presented. In this study, an enclosure filled with an absorbing, emitting and scattering medium with diffusely emitting and reflecting opaque boundaries is considered. The finite volume method is applied to solve the radiative transfer equation in order to simulate the measured incident radiation values which are used as input data for the inverse analysis. The conjugate gradient method is adopted for the estimation of wall emissivities by minimizing the objective function at each iteration step. To verify the performance of the unstructured grid system, we compare the results with those using a structured grid system for the two-dimensional lopsided shape. The effect of measurement errors on the estimation accuracy is also investigated.

Basic Analysis of Bubble Behavior in the Viscous Flow Domain with the Free Interface (자유표면을 가지는 점성 유동장내의 기포거동에 관한 기초해석)

  • I.R. Park;H.H. Chun
    • Journal of the Society of Naval Architects of Korea
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    • v.39 no.1
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    • pp.16-27
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    • 2002
  • A level-set method is used for analyzing the behaviors of gas bubbles in two fluids incompressible viscous flow domain. The governing equations are solved by using a finite volume method. The numerical results are verified by comparing with the experimental and other computational results. Computations for the deformations and motions of one or multi-bubbles in the flow domain with the initial undisturbed free interface are conducted. It can be seen that numerical results for different surface tension and density ratio arise very different behaviors of bubbles. When bubbles rise near the free interface, the free interface gives some great influence on the behaviors of bubbles. The present results computed by a level-set method give useful information about the properties of bubble motions and deformations.

Development of GPU-accelerated kinematic wave model using CUDA fortran (CUDA fortran을 이용한 GPU 가속 운동파모형 개발)

  • Kim, Boram;Park, Seonryang;Kim, Dae-Hong
    • Journal of Korea Water Resources Association
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    • v.52 no.11
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    • pp.887-894
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    • 2019
  • We proposed a GPU (Grapic Processing Unit) accelerated kinematic wave model for rainfall runoff simulation and tested the accuracy and speed up performance of the proposed model. The governing equations are the kinematic wave equation for surface flow and the Green-Ampt model for infiltration. The kinematic wave equations were discretized using a finite volume method and CUDA fortran was used to implement the rainfall runoff model. Several numerical tests were conducted. The computed results of the GPU accelerated kinematic wave model were compared with several measured and other numerical results and reasonable agreements were observed from the comparisons. The speed up performance of the GPU accelerated model increased as the number of grids increased, achieving a maximum speed up of approximately 450 times compared to a CPU (Central Processing Unit) version, at least for the tested computing resources.

A Study on the Flow Characteristics according to the Change of Structure in Filtration Using the Numerical Model (수치모형을 이용한 여과기 내 구조 변경에 따른 유동특성 연구)

  • Kim, Taewon;Song, Sooho;Choi, Changhyung;Park, Youngjin;Kim, Jiho
    • Proceedings of the Korea Water Resources Association Conference
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    • 2017.05a
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    • pp.285-285
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    • 2017
  • 최근 전 세계적으로 심각해지는 물 부족 현상과 수질오염으로 대량의 원수를 빠른 시간 내에 여과하기 위한 여과장치의 개발 및 효율성 향상을 위한 연구의 필요성이 증가되고 있다. 특히 여과필터의 내부구조에 의해 유동이 편중되는 현상이 발생하면 여과효율 및 여과필터 유지관리에 문제가 발생되기 때문에 최적의 여과필터를 설계하는 것이 중요하다. 이에 본 연구에서는 수리모형실험으로 검토하기에 어려움이 있는 여과기 내부구조에 대한 유동특성을 수치해석을 이용하여 검토하였다. 수치해석은 유한요소법 기반의 수치모형으로 여과기 내부를 상세하게 모의할 수 없기 때문에 유한체적법 기반인 ANSYS CFX 모형을 이용하였다. 여과기 내 여과필터는 두께 2.0 mm, 공극율 25%로 가정하고 다공성 기법(porous media)을 적용하였다. 검토를 위한 경계조건은 유입부에 목표 취수량, 유출부에 대기압 조건을 적용하였으며, 여과기에 비해 매우 작게 구성된 여과필터 내부의 유동특성을 검토하기 위해 여과기는 최소 3.0 mm, 여과필터는 1.0 mm의 격자를 적용하였다. 현재 실제 여과시설에 적용되고 있는 여과기 제품 형상을 기준으로 여과기 내부 흐름공간의 크기 및 각도 조정에 따른 유동특성을 검토하여 여과효율을 비교하였으며 통과유량, 유속, 유속벡터 등을 검토하여 균등한 유량과 유속이 발생되는 최적의 여과장치 구조를 도출하였다. 본 연구에서 여과기 내부 구조 변경에 따른 유동특성 검토를 통해 도출된 최적의 여과기 내부크기 및 각도에 대한 설계인자는 여과기 내 여과필터의 효율을 증가시킬 뿐만 아니라 내구성 증진에 도움이 될 것으로 예상된다.

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Numerical Simulation of Subaerial and Submarine Landslides Using the Finite Volume Method in the Shallow Water Equations with (b, s) Coordinate ((b, s) 좌표로 표현된 천수방정식에 유한체적법을 사용하여 해상 및 해저 산사태 수치모의)

  • Pham, Van Khoi;Lee, Changhoon;Vu, Van Nghi
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.4
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    • pp.229-239
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    • 2019
  • A model of landslides is developed using the shallow water equations to simulate time-dependent performance of landslides. The shallow water equations are derived using the (b, s) coordinate system which can be applied in both river and ocean. The finite volume scheme employing the HLL approximate Riemann solver and the total variation diminishing (TVD) limiter is applied to deal with the numerical discontinuities occurring in landslides. For dam-break water flow and debris flow, numerical results are compared with analytical solutions and experimental data and good agreements are observed. The developed landslide model is successfully applied to predict subaerial and submarine landslides. It is found that the subaerial landslide propagates faster than the submarine landslide and the speed of propagation becomes faster with steeper bottom slope and less bottom roughness.