• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.908-911
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• 2004

The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers. In this study, two dimensional unite element model, SMS, is used to simulate a complex flow along with the sediment movements in the natural river. The RMA-2 model embeded in SMS is used to simulate flow phenomena and SED-2D model is employed to simulate sediment transport. The model is applied to the confluence zone of the Gam River and mouth of Nakdong River. For model calibration, the result of the unsteady flow analysis is compared with the Typhoon 'Rusa' data. In addition, the runoff analysis was conducted for the determination of the project flood and the flood forecasting. The simulation results presented the characteristics of two dimensional flow with velocity vector and flow depth. The sediment transport characteristics are shown in terms of sediment concentration as well as bed elevation change. Accordingly, the SMS model in this study turned out to be very effective tool for the simulation of the hydrodynamic characteristics under the various flow conditions and corresponding sediment transports in natural rivers.

• 한국해양환경ㆍ에너지학회지
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• 제14권2호
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• pp.121-129
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• 2011

EFDC 모형에서 해수유동과 퇴적물 이동을 모의하고자 하는 경우에 필요한 해수유동과 퇴적물 이동 모듈외의 수질 모델 등의 요소가 해수유동 모의시간에 미치는 영향을 검토하였다. 해수유동과 퇴적물 이동의 계산에 불필요한 수질요소관련 프로그램과 조건문 들을 모델에서 제거하는 방법으로 모형을 간략화하고 계산시간을 비교하였다. 수정된 EFDC 모형(EFDC-E)을 사용하여 목포해역에서 조류에 대하여 모의하고, 계산에 소요되는 시간과 모의결과를 EFDC 모형을 이용한 모의결과와 비교하였다. 또한, 2차원 모형과 3차원 모형을 동시에 적용하여 2차원 모의결과와 3차원 모의결과의 차이점에 대한 분석과 각 모형의 목포해역 조류 비대칭에 대한 재현성에 대해서 검토하였다. 간략화과정을 통해서 개선된 EFDC-E 모형은 EFDC 모형보다 2차원과 3차원 조류모의에서 약 3배 빠르게 계산하는 것을 확인할 수 있었다. 2차원 모의결과는 수심평균유속을 계산하여 상층에서 관측한 조류를 정확하게 재현하지 못하였으나, 3차원 모형을 적용한 결과는 2차원 모의보다 유속크기가 관측치와 보다 잘 일치하는 모습을 보였다.

• 물과 미래
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• 제26권3호
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• pp.87-101
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• 1993

하천에서의 동수역학적 유동해석을 위하여 2차원 천수방정식을 기본방정식으로 하고 이를 불연속구간함수와 upwinding weighting을 도입한 감쇠형 Galerkin 방법에 의하여 해석하는 RIV-FEM2를 개발하였다. RIV-FEM2는 전처리, 주처리, 후처리 과정으로 구성되었으며, 전처리와 주처리 과정은 Fortran-77으로, 후처리 과정은 turbo-Pascal에 의하여 각각 처리할 수 있도록 개발하였다. 2차원의 만곡부, 교량부, 축소부를 가진 대칭수로부등의 경우와 실제 하천에 대하여 본 모형을 적용한 결과 유속분포, 수면형 및 질량 유출입량 보존등의 면에서 안정성과 효율성이 우수하게 나타나 본 모형의 적용성을 입증할 수 있었다. 본 모형은 실제 하천의 이수 및 치수관리에 기여할 수 있을 것으로 판단된다.

• 한국물환경학회지
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• 제27권5호
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• pp.710-718
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• 2011

An integrated water quality management of reservoir and river would be required when the quality of downstream river water is affected by the discharge of upstream dam. In particular, for the control of downstream turbidity during flood events, the integrated modeling of reservoir and river is effective approach. This work was aimed to develop a laterally-averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2), by which water quality can be predicted in the downstream of Yongdam dam in conjunction with the reservoir model, and to validate the model under two different hydrological conditions; wet year (2005) and drought year (2010). The model results clearly showed that the simulated data regarding water elevation and suspended solid (SS) concentration are well corresponded with the measured data. In addition, the variation of SS concentration as a function of time was effectively simulated along the river stations with the developed model. Consequently, the developed model can be effectively applied for the integrated water quality management of Yongdam dam and downstream river.

• 한국환경과학회지
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• 제17권9호
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• pp.957-968
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• 2008

The purpose of this study is to analyze the characteristics of hydraulic behavior of the natural channel flow according to the temporal classification mode, and thus propose the hydraulic analysis method for future channel design. For analysis, the temporal flow characteristics of the channel section was divided into the steady flow and the unsteady flow. For hydraulic analysis, the HEC-RAS model, which is a one-dimensional numerical analysis model, and the SMS-RAM2 model, which is a two-dimensional model, were used and the factors used for analysis of hydraulic characteristics were flood elevation and flow rate. The flow state was analyzed on the basis of the one-dimensional steady flow and unsteady flow for review. In the unsteady flow analysis the flow rate changed by $(-)0.16%{\sim}(+)0.26%$, and the flood elevation varied by $(-)0.35%{\sim}(+)0.51%$ as compared to the values in the steady flow analysis. Given these results, in the one-dimensional flow analysis based on the unsteady flow the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow. The flow state was analyzed on the basis of the two-dimensional steady flow and unsteady flow. In the unsteady flow analysis the flow rate varied by $(-)0.16%{\sim}(+)1.08%$, and the flood elevation changed by $(-)0.24%{\sim}(+)0.41%$ as compared to the values in the steady flow analysis. Given these analysis results, in the two dimensional flow analysis based on the unsteady flow, the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1995년도 정기학술강연회 발표논문 초록집
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• pp.108-109
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• 1995

Hypoxia has persisted during summer in the bottom water of the lower portion of the Rappahannock Estuary, a western shore tributary of Chesapeake Bay. A laterally integrated two-dimensional, real-time model, consisting of linked hydrodynamic and water quality models, was developed to study the contributing processes for hypoxia. The hydrodynamic model gives the information of physical transport processes, both advective and diffusive, to the water quality model, which simulates the spatial and temporal distributions of eight water quality state variables. (omitted)

• 한국전산유체공학회지
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• 제12권4호
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• pp.44-53
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.

• 대한토목학회논문집
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• 제31권6B호
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• pp.515-522
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• 2011

수리해석 모형들은 하천의 흐름에 대한 연구에 이용되거나, 수공구조물의 설계 및 하천의 설계 등 실무에 널리 사용되고 있다. 이들 수리해석 모형은 실측자료를 통한 보정이 필요하나, 홍수시 유속을 측정하는 것 자체가 위험한 작업이기 때문에 홍수시 하천의 2차원 유속분포에 대한 실측자료가 전무한 실정이다. 이러한 이유로 2차원 수치모형의 결과는 보통 몇 개 지점의 실측된 자료를 비교함으로써 보정 및 검증을 실시하고 있다. 더욱이 설계 홍수량에 대한 모형의 보정은 1차원 모형인 HEC-RAS의 모의결과를 이용하여 보정하고 있다. 본 연구에서는 일본의 토네강(Tone river)에서 홍수시 촬영한 항공사진을 분석하여 추출한 유속벡터 자료를 이용하여 하천설계 실무 및 연구 등에 널리 사용되어지고 있는 2차원 수치모형인 RAMS의 RAM2, SMS의 RMA2와 1차원 모형인 HEC-RAS 모형의 검증을 실시하였다. 또한, HEC-RAS결과를 이용한 2차원 모형의 보정에 대한 타당성을 검토하였다. 검토결과, HEC-RAS 및 RAM2, RMA2 모형의 수위모의 결과 모두 관측점의 수위와 비슷한 결과을 보이고 있었으나, 유속모의의 경우 고수부지에서의 2차원 모형에 의한 유속결과와 항공사진으로부터 추출된 유속결과가 차이를 보이고 있었다. 또한, 1차원 모형에 의한 결과와 항공사진으로부터 추출된 유속장을 단면평균한 유속과 비교한 결과 큰 오차가 발생하고 있는 것으로 나타났다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

• Nuclear Engineering and Technology
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• 제31권3호
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• pp.344-363
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• 1999

A multi-dimensional thermal-hydraulic system analysis code, MARS 1.3.1, has been developed in order to have the realistic analysis capability of two-phase thermal-hydraulic transients for pressurized water reactor (PWR) plants. As the backbones for the MARS code, the RELAP5/MOD3.2.1.2 and COBRA-TF codes were adopted in order to take advantages of the very general, versatile features of RELAP5 and the realistic three-dimensional hydrodynamic module of COBRA-TF. In the MARS code, all the functional modules of the two codes were unified into a single code first. Then, the source codes were converted into the standard Fortran 90, and then they were restructured using a modular data structure based on "derived type variables" and a new "dynamic memory allocation" scheme. In addition, the Windows features were implemented to improve user friendliness. This paper presents the developmental work of the MARS version 1.3.1 including the hydrodynamic model unification, the heat structure coupling, the code restructuring and modernization, and their verifications.their verifications.