• Title/Summary/Keyword: 입자추적

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A Study on the Influence of the Saemangeum Sluice-Gates Effluent Discharge using the Particle Tracking Model (입자추적 실험을 이용한 새만금 배수갑문 유출수의 영향 범위 연구)

  • Cho, Chang Woo;Song, Yong Sik;Bang, Ki Young
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.4
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    • pp.211-222
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    • 2020
  • This study suggested a method calculating the influence of effluent discharge from Saemangeum sluice-gates using the particle tracking model. For 2017, we presented the seasonal effects of effluent discharge as probability spatial distributions and compared with the results of the water age, one of the indicators of transport time scale. The influence of sluice-gates effluent discharge increases radially around Sinshi or Gaseok gates, which are expected to be biased toward the south in winter and north in summer due to the effect of seasonal winds. Although the results of the prediction are limited to the 2017 situation, the method of calculating the influence of sluice-gates effluent discharge using the Lagrangian particle tracking model can be used to predict the future of the around Saemangeum.

A Particle Tracking Method for the Lagrangian-Eulerian Finite Element Method in 3-D Subsurface System (3차원 지표하 시스템에서 Lagrangian-Eulerian 유한요소법에 대한 입자추적 알고리즘)

  • Lee, Jae-Young;Kang, Mee-A
    • The Journal of Engineering Geology
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    • v.19 no.2
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    • pp.205-215
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    • 2009
  • The conventional numerical models to analyze flow in subsurface porous media under the transient state usually generate numerical oscillation and unstability due to local flux domain for critical cases such as infiltration into initially dry soil during rainfall period. In this case, it is required refined mesh and small time step, but it decrease efficiency of computation. In this study, numerical unstability in discontinuity domain is removed by applying particle tracking algorithm to simulate unsteady subsurface flow with inflow boundary condition. Finally the hybrid LE FEM improving numerical stability is proposed. The hypothetical domains with unsteady uniform and nonuniform flow field were used to demonstrated algorithm verification. In comparison with analytic solution, we obtained reasonable results and conducted simulation of hypothetical 3-D recharge/pumping area. The proposed algorithm can simulate saturated/unsaturated porous media with more practical problems and will greatly contribute to accuracy and stability of numerical computation.

Development of new integrated particle tracking techniques combining the numerical method, semi-analytical method, and analytical method (수치, 해석적, 준 해석적 및 해석적 방법을 통합한 새로운 입자추적기술 개발)

  • Suk, Hee-Jun
    • Journal of Soil and Groundwater Environment
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    • v.13 no.6
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    • pp.50-61
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    • 2008
  • In this study, new integrated particle tracking algorithm was developed to reduce the inherent problem of Eulerian- Lagrangian method, or adverse effect of particle tracking error on mass balance error. The new integrated particle tracking algorithm includes numerical method, semi-analytical method, and analytical method which consider both temporal and spatial changes of velocity field during time step. Detail of mathematical derivations is well illustrated and four examples are made to verify through the comparison of the new integrated particle tracking with analytical solution or Runge-Kutta method. Additionally, It was shown that the there is better superiority of the new integrated particle tracking algorithm over other existing particle tracking method such as Lu's method.

Ocean Outfall Modelling with the Particle Tracking Method (입자추적법을 이용한 해양방류구 모델링)

  • Jung, Yun-Chul
    • Journal of Navigation and Port Research
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    • v.26 no.5
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    • pp.563-569
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    • 2002
  • To overcome the weaknesses of conventional finite difference model in pollutant dispersion modelling, the particle tracking method is used. In this study, a three dimensional particle tracking model which can be used in Princeton Ocean Model was developed and verified through the various numerical tests. Usability of the model was also confirmed through the ocean outfall modelling in Tampa Bay, Florida. As it is expected, random walk model showed the less dispersion in a range compared to the conventional finite difference model and its reason is estimated due to an error from numerical diffusion which the conventional model holds. This newly developed model is expected to be used in various ocean dispersion modelling.

Lagrangian Investigation of Turbulent Channel Flow (I) - An Assessment of Particle Tracking Algorithms - (난류채널유동의 라그란지안 해석 (I)- 입자추적 알고리듬 평가 -)

  • Choi, Jung-Il;Lee, Chang-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.859-866
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    • 2003
  • The Lagrangian dispserion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Fluid particle velocity and acceleration along a particle trajectory are computed by employing several interpolation schemes such as linear interpolation, high-order Lagrange polynomial interpolation and the Hermite interpolation schemes. The performances of the schemes are evaluated through comparison of errors in computed particle positions, velocities and accelerations against spectral interpolation. Adopting the four-point Hermite interpolation in the homogeneous directions and Chebyshev polynomials in the wall-normal direction appears to produce most reliable Lagrangian statistics including acceleration correlations with a reasonable amount of computational overhead.

Analysis of Hydrodynamic Change around the Saemangeum Area Using a Particle Tracking Method (입자추적방법을 이용한 새만금 해역의 수리특성 변화 분석)

  • Suh, Seung-Won;Lee, Hwa-Young
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.6
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    • pp.442-450
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    • 2011
  • A three dimensional random walk particle tracking method is applied to the Saemangeum area in order to find stepwise environmental changes according to long term construction. Flow regime around Mangyeong, Dongjin and Geum river estuary changed greatly due to dike construction. It is distinctive that reduction of Byeonsan area's flow field and stagnant change in the northern part of the inner reservoir. Similar characteristics are found through the tidal excursion analysis. By analysis of the vertical mixing structures according to density stratification based on temperature and salinity variation, a salt wedge and very strong stratification arises in the inner part of the reservoir after final closure, while it has been well mixed or partially mixed estuary during construction. Shrinking of horizontal dispersion and vertical mixing capability may cause adverse effect on water quality not only inner part but also outer region of the Saemangeum reservoir.

Flow Propagtion Characteristics from Weir Discharge Conditions by Applying 2-D Hydraulic Model (2차원 모형 이용한 보 방류조건에 따른 흐름전달특성)

  • Kim, Hyeon Il;Han, Kun Yeun;Lee, Jae Yeong;Kim, Beom Jin
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.477-477
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    • 2017
  • 국내 4대강사업 이후의 하천환경의 변화를 고려한 보 구간 별 도달시간 재산정이 필요하며, 더욱이 다기능 보의 영향을 고려한 도달시간에 대한 연구도 필요한 실정이다. 또한 4대강사업 이후 설치된 다기능 보의 기존 방류를 이용한 보 운영은 관리수위를 유지하기 위해 유입된 수량만을 방류시켜 수온차가 있는 성층파괴에는 한계가 있었다. 이러한 문제점으로 펄스 방류는 수질개선을 위하여 제시된 인위적 반복적 방법으로 하천의 유량 및 유속을 증대시켜 하천 상 하층을 혼합하여 성층을 파괴함으로써 조류의 성장을 억제하기 위한 목적으로 적용될 수 있으며, 실제 하천에 적용하기에 앞서 보 방류조건에 따른 흐름전달특성의 분석과 검증이 필요하다. 이에 본 연구에서는 4대강사업 이후의 하도에 대한 지형자료와 상세한 보주변의 지형자료를 이용하여 수리학적 모형을 위한 하도자료를 구축하였으며, 보 운영을 고려하여 2차원 수리해석을 실시하였다. 보 방류조건에 따른 흐름전달특성 분석에 앞서 각 보 구간별 거리를 산정하였다. 또한 일정 방류 시나리오 유량조건을 이용하여 각 보 구간별 도달시간을 산정하였으며, 산정된 도달시간은 HEC-RAS를 통해 모의된 계산결과와 비교 및 한국수문조사연보 유량편의 평균유속과의 비교 및 검증을 실시하였다. 또한 펄스 방류에 따른 흐름의 전달특성을 분석을 하였으며, 분석한 결과와 보 하류 주요지점에서의 수위 관측결과를 2차원 수리모형에서 확인 할 수 있었다. 또한 2차원 수리모형 내에서 입자를 적용하여 입자추적을 통한 보 하류부의 흐름전달 양상을 해석하였다. 본 연구를 통하여 유량 규모 및 등급별 방류량을 고려하여 적용 가능한 간편 도달시간을 제안 및 산정하여 현장에서 실무적으로 사용가능한 자료를 제공함으로써 하천 유지 및 관리에 이용이 가능할 것이라 판단된다. 또한 펄스 방류에 따른 흐름의 전달특성을 분석함으로써, 특정 방류량에 따른 흐름특성을 이해하고 후에 수질개선 효과 분석 및 다양한 방류시나리오에 따른 보의 운영 지침에 기초자료를 제공할 수 있을 것으로 판단된다.

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