• Title/Summary/Keyword: 파랑 수치모형

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이어도 기지에서 관측된 파랑 자료로부터 주변 대표파랑 자료로의 복원기술 검토

  • 이정렬;이동영
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.1439-1444
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    • 2004
  • 이어도 기지에서 관측된 파랑 자료는 주변 수중 암초 또는 지형의 영향을 받으므로 수중 암초의 영향을 받지 않는 지역을 대표하는 주변 대표 파랑 자료로의 환산이 필요할 수 있다. 이를 위하여 본 연구에서는 이론적인 쇄파 모형(Lee, 1993)을 통하여 변환기술상 문제점을 파악하고 원형 천퇴에서의 수치실험을 통하여 천퇴 후면에서 파랑의 변형 정도를 파고비를 통하여 분석하였으며 이를 토대로 이어도 수중 암초에서의 파랑 변형이 관측 지점의 파고에 리치는 영향을 평가하였고 그 결과를 관측 치와 비교${\cdot}$분석하였다.

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Applicability of Boussinesq Models for Wave Deformation and Wave-Induced Current (파랑변형 및 해빈류에 대한 Boussinesq 모형의 적용성 검토)

  • Cho, Young-Jun;Park, Il-Heum
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.16 no.2
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    • pp.185-193
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    • 2010
  • In the present study, wave deformation and wave-induced current were calculated under the regular wave conditions using the Boussinesq model. The model results of the wave deformation showed good agreements with the preceeding laboratory experiments of others. The wave-induced current of the fully developed sea state was calculated. For field application of model, the preceeding field data by others in the real scale of the water area were compared, the numerical result of wave deformation showed a relatively good agreement with the field data. Although the numerical result of wave-induced current was underestimated over the longshore bar developed area, the Boussinesq model is generally suitable to predict the wave-induced current.

Simulation of Wave-Induced Currents by Nonlinear Mild-Slope Equation (비선형 완경사 방정식에 의한 연안류의 모의)

  • 이정렬;박찬성;한상우
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.1
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    • pp.46-55
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    • 2001
  • An approach using the nonlinear wave model in predicting wave-induced currents is presented. The model results were compared with those of the conventional model using phase-averaged radiation stress, and in addition with experimental data captured by a PIV system. As a result of comparison of wave-induced currents generated behind the surface-piercing breakwater and submerged breakwater, eddy patterns appeared to be similar each other but in general numerical solutions of both models were underestimated.

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A Numerical Study on Characteristics of Flood Wave Passing through Urban Areas (1) : Development and Verification of a Numerical Model (도시지역을 관통하는 홍수파의 특성에 관한 수치적 연구 (1) : 수치모형의 개발 및 검증)

  • Jeong, Woo-Chang;Lee, Jin-Woo;Cho, Yong-Sik
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.6
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    • pp.89-97
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    • 2009
  • In this study, a two-dimensional unstructured finite volume model based on the shallow-water equations and well-balanced HLLC scheme is developed. The model is verified by applying to various one- and two-dimensional problems related to the analyses of dam-break wave. The predicted numerical results agree very well with available analytical solutions and laboratory measurements. The model provides slightly more accurate results compared with the existing models.

Implications and numerical application of the asymptotical shock wave model (점진적 충격파모형의 함축적 의미와 검산)

  • Cho, Seong-Kil
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.11 no.4
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    • pp.51-62
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    • 2012
  • According to the Lighthill and Whitham's shock wave model, a shock wave exists even in a homogeneous speed condition. They referred this wave as unobservable- analogous to a radio wave that cannot be seen. Recent research has attempted to identify how such a counterintuitive conclusion results from the Lighthill and Whitham's shock wave model, and derive a new asymptotical shock wave model. The asymptotical model showed that the shock wave in a homogenous speed traffic stream is identical to the ambient vehicle speed. Thus, no radio wave-like shock wave exists. However, performance tests of the asymptotical model using numerical values have not yet been performed. We investigated the new asymptotical model by examining the implications of the new model, and tested it using numerical values based on a test scenario. Our investigation showed that the only difference between both models is in the third term of the equations, and that this difference has a crucial role in the model output. Incorporation of model parameter${\alpha}$ is another distinctive feature of the asymptotical model. This parameter makes the asymptotical model more flexible. In addition, due to various choices of ${\alpha}$ values, model calibration to accommodate various traffic flow situations is achievable. In Lighthill and Whitham's model, this is not possible. Our numerical test results showed that the new model yields significantly different outputs: the predicted shock wave speeds of the asymptotical model tend to lean toward the downstream direction in most cases compared to the shock wave speeds of Lighthill and Whitham's model for the same test environment. Statistical tests of significance also indicate that the outputs of the new model are significantly different than the corresponding outputs of Lighthill and Whitham's model.

Transformation of Regular Waves on Currents in Water of Slowly Varying Depth-Theoretical Study (흐름이 존재하는 완경사 해역에서의 파랑변형-이론적 고찰)

  • 채장원;정신택;엄대기;안한수
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.1 no.1
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    • pp.1-7
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    • 1989
  • Theoretical studies have been made to analyze combined refraction diffraction of the wind waves propagating on a large scale current in water of varying depth. The governing equation for monochromatic waves was derived through splitting a mild slope equation into two equations. A numerical model is developed using finite difference scheme which is computationally very efficient for modelling large area. Numerical examples concerning the interactions between waves and rip currents over a gentle slope are presented, in which the current effects on the wave diffraction in the caustic region are closely examined.

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Kinematic Wave Rainfall-Runoff Model Using CUDA FORTRAN (CUDA FORTRAN을 이용한 운동파 강우유출모형)

  • Kim, Boram;Kim, Dae-Hong
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.271-271
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    • 2018
  • 그래픽 처리 장치(GPU: Graphic Processing Units)는 그래픽 처리에 특화된 수많은 산술논리연산자 (ALU: Arithmetic Logic Unit)와 이에 관련된 인스트럭션Instruction)으로 인해 중앙 처리 장치(CPU: Central Processing Units) 보다 훨씬 빠른 계산 처리를 수행할 수 있다. 최근에는 FORTRAN에 의해 구현된 많은 수치모형들이 현실적인 모델링 방법의 발달로 인해 더 많은 계산량과 계산시간을 필요로 한다. 이 연구에서는 GPU 상의 범용 계산GPGPU : General-Purpose computing on Graphics Processing Units) 기반 운동파 강우유출모형(Kinematic Wave Rainfall-Runoff Model)이 CUDA(Compute Unified Device Architecture) FORTRAN을 사용하여 구현되었다. CUDA FORTRAN 운동파 강우유출모형의 계산 결과는 검증된 CPU 기반 운동파 강우유출모형의 계산 결과와 비교하여 검증되었으며, 잘 일치함을 보여 주었다. CUDA FORTRAN 운동파 강우유출모형은 CPU 기반 모형에 비해 약 20 배 더 빠른 계산 시간을 보였다. 또한 계산 영역이 커짐에 따라 CPU 버전에 비해 CUDA FORTRAN 버전의 계산 효율이 향상되었다.

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A Numerical Model of Nonlinear Stream Function Wave Theory by the Least Squares Method (최소자승법을 사용한 유량함수 비선형 파랑이론의 수치모형)

  • 서승남
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.6 no.4
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    • pp.340-352
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    • 1994
  • A numerical model of nonlinear stream function wave theory evolved from Dean's model (1965) is presented. The stream function theory has been evaluated to be an accurate and useful tool for engineering applications. Effects of damping coefficient employed in a linearized simultaneous equation and number of points in the numerical integration of model on numerical solutions are assessed. Most accurate wave characteristics calculated by the present model are tabulated using revised Dean's Table (Chaplin, 1980) input parameters. Since the well-known feature of nearly breaking waves that with increasing wave steepness the wave length as well as integral properties have a maximum prior to the limiting wave height is represented by the model, the accuracy of model can be proved.

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A Review on Lateral Driving Boundary of the Numerical Model Using Time-Dependent Mild Slope Equation (시간의존 완경사방정식을 이용한 파랑변형 수치모형의 측방입사경계의 처리)

  • 김인철;편종근
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.7 no.2
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    • pp.141-147
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    • 1995
  • Various numerical models for predicting wave deformation have been proposed. Among them a time-dependent mild-slope equation based on the line discharges and surface-elevation changes has been widely used in the wave fields with reflective waves. If applying this model to the case of obliquely-incident waves, not only the open-sea boundary but also one of the lateral boundaries should be treated as incident boundaries. In this study, Maruyama and Kajima (1985), Copeland (1985) and Ohnaka and Watanabe (1987)'s method are reviewed and the characteristics of these methods are analyzed using e normalized wave heights, wave angels and phases obtained from the numerical experiments. It is shown that Ohnaka and Watanabe(1987)'s method provides the most adequate driving boundary is the most suitable in e wave field with a general bottom slope.

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Application of Numerical Model - FLUMEN to Inundation (FLUMEN 모형의 홍수범람 적용성 검토)

  • Bae, Yong-Hoon;Cho, Yong-Sik
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.1376-1380
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    • 2004
  • 본 연구에서는 홍수범람지도 제작을 위해 사용되는 수치모형의 검증을 수행하고자 한다. 검증할 수치모형은 스위스의 Beffa에 의해 개발된 FLUMEN(FLUvial Modeling ENgine)으로서 수심 적분된 2차원 비선형 천수방정식에 불규칙 심각망을 이용한 유한체적법(finite volume method)이 적용된 수치모형이며 스위스, 독일, 오스트리아 등에서 홍수범람해석에 사용된 바 있는 모델이다. FLUMEN 모형의 검증을 위하여 범람해석시 가장 중요한 문제인 이동경계조건(moving boundary condition)을 포함하고 있는 원형섬에서의 고립파에 처오름높이를 계산하여 수리모형실험 결과와 비교한다. 수리모형실험은 미국 육군 공병단 산하의 해안공학연구소(CERC, Coastal Engineering Research Center)에서 수행되었으며(Liu 등, 1995) 수조의 중앙에 높이 0.625m, 해저지름 7.2m, 경사각 $14.04^{\circ}$의 원형섬이 위치한다. 본 연구 결과, 수치해석으로 계산된 섬에서의 실제 처오름높이와 입사파의 파고의 비(R/A)는 수리모형실험의 결과와 어느 정도 일치하였다.

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