• Title/Summary/Keyword: FLOW-3D 모형

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Estimation of ecological flow and fish habitats for Andong Dam downstream reach using 1-D and 2-D physical habitat models (1차원 및 2차원 물리서식처 모형을 활용한 안동댐 하류 하천의 환경생태유량 및 어류서식처 추정)

  • Kim, Yongwon;Lee, Jiwan;Woo, Soyoung;Kim, Soohong;Lee, Jongjin;Kim, Seongjoon
    • Journal of Korea Water Resources Association
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    • v.55 no.12
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    • pp.1041-1052
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    • 2022
  • This study is to estimate the optimal ecological flow and analysis the spatial distribution of fish habitat for Andong dam downstream reach (4,565.7 km2) using PHABSIM (Physical Habiat Simulation System) and River2D. To establish habitat models, the cross-section informations and hydraulic input data were collected uisng the Nakdong river basic plan report. The establishment range of PHABSIM was set up about 410.0 m from Gudam streamflow gauging station (GD) and about 6.0 km including GD for River2D. To select representative fish species and construct HSI (Habitat Suitability Index), the fish survey was performed at Pungji bridge where showed well the physical characteristics of target stream located downstream of GD. As a result of the fish survey, Zacco platypus was showed highly relative abundance resulting in selecting as the representative fish species, and HSI was constructed using physical habitat characteristics of the Zacco platypus. The optimal range of HSI was 0.3~0.5 m/s at the velocity suitability index, 0.4~0.6 m at the depth suitability index, and the substrate was sand to fine gravel. As a result of estimating the optimal ecological flow by applying HSI to PHABSIM, the optimal ecological flow for target stream was 20.0 m3/sec. As a result of analysis two-dimensional spatial analysis of fish habitat using River2D, WUA (Weighted Usable Area) was estimated 107,392.0 m2/1000 m under the ecological flow condition and it showed the fish habitat was secured throughout the target stream compared with Q355 condition.

Optimal Parameters Estimation of Diffusion-Analogy Geomorphologic Instantaneous Unit Hydrograph Model (확산-유추 지형학적 순간단위도 모형의 최적매개변수 추정)

  • Kim, Joo-Cheol;Choi, Yong-Joon
    • Journal of Wetlands Research
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    • v.13 no.3
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    • pp.385-394
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    • 2011
  • In this study, optimal parameters of diffusion-analogy GIUH were calculated by separating channel and hillslope from drainage structures in the basin. Parameters of the model were composed of channel and hillslope, each velocity($u_c$, $u_h$) and diffusion coefficient($D_c$, $D_h$). Tanbu subwatershed in Bocheong river basin as a target basin was classified as 4th rivers by Strahler's ordering scheme. The optimization technique was applied to the SCE-UA, the estimated optimal parameters are as follows. $u_c$ : 0.589 m/s, $u_h$ : 0.021 m/s, $D_c$ : $34.469m^2/s$, $D_h$ : $0.1333m^2/s$. As a verification for the estimated parameters, the error of average peak flow was about 11 % and the error of peaktime was 0.3 hr. By examining the variability of parameters, the channel diffusion coefficient didn't have significant effect on hydrological response function. by considering these results, the model is expected to be simplified in the future.

Flow Characteristics and Riverbed Change Simulation on Bridge-intensive Section (교량밀집 구간의 흐름특성과 하상변동 모의)

  • Cho, Hong Je;Jeon, Woo Yeol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.6B
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    • pp.589-598
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    • 2010
  • When the hydraulic structures, such as bridge and weir, are consecutively installed to a short section of a river with complicated cross section, analyzing the flow characteristics and the riverbed change modality of the river is very important. In the 250 m section of the Taehwa river near the Samho-bridge, which passes through Ulsan city, three bridges has been installed, and the tributary water is flowing into both up and downstream of the section. Due to these factors, when the flood occurs, the cross section of the river changes vastly by the water level change and scour. Even so, due to the fact that the Samho-bridge divides the section into two parts, the national river and the regional river, each part is being analyzed separately by the onedimensional model. In this study, the flow characteristics due to the bridge concentration and the tributary water inflow were jointly analyzed for both up and downstream by using the one-dimensional HEC-RAS model and the two-dimensional SMS model, such as RMA2. The riverbed change modality of the section was also investigated by using the SED2D model. The results showed that the water level difference between the HEC-RAS and RMA2 was 0.87 m when applied to the three consecutive bridges. The riverbed change simulation using SED2D showed that the maximum scour was 0.231 m and it occurred at the Samho-bridge, which located in the middle and has short pier distance. In conclusion, when planning the river maintenance for the regions with concentrated bridges or the sections with severe changes in cross-section and flow, estimating the flood elevation by two-dimensional model and establishing countermeasures for the scouring of the bridge are required. In addition, an integrated analysis on both the national river and the regional river is necessary.

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 a 3-D Viscous Flow Solver Based on Unstructured Hybrid Meshes (비정렬 혼합 격자계 기반의 삼차원 점성 유동해석코드 개발)

  • Jung, Mun-Seung;Kwon, Oh-Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.8
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    • pp.677-684
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    • 2007
  • In the Present Study, a 3-D viscous flow solver, based on unstructured hybrid meshses containing tetrahedra, prisms and pyramids, has been developed. A finite-volume discretization scheme is used for solving the compressible Navier-Stokes equations. A cell-vertex median dual volume is used for spatial discretization. The one-equation Spalart-Allmaras turbulence model has been adopted to evaluate the eddy viscosity. Validation were made by computing laminar and turbulent flows around a 3-D wing for steady flows and turbulent flows around an oscillating 3-D wing in harmonic motion for unsteady flows.

Comparison of Numerical Results for Stability Assessment of Revetments in Meandering Channel (만곡부 사석보호공 안정성 평가를 위한 수치모의결과 비교)

  • Kim, Hyung-Jun;Bae, Deok-Won;Yoon, Kwang-Seok
    • Proceedings of the Korea Water Resources Association Conference
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    • 2012.05a
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    • pp.605-605
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    • 2012
  • 최근 통계자료에 의하면 국내 제방붕괴 유형 중 11.5%가 제체 불안정에 의한 붕괴로 보고되고 있다. 홍수시 노후화된 제방이 붕괴하여 발생하는 인명 및 재산피해는 점차 증가하고 있는 상황이어서, 이에 대한 제방 시설물의 보강 및 안전관리 대책이 필요한 상황이다. 하천시설물 주변의 흐름특성에 의하여 세굴이 발생할 수 있는 지점에는 보호공을 설치하여 시설물의 안정성을 확보하도록 하천설계기준 해설(2009)에서 제안하고 있다. 그러나 구조물을 보완하는 보호공의 공종 및 규격 등을 설계하기 위한 세부적인 설계지침이 미흡하여 외국의 연구 또는 설계사례를 참고하여 국내 하천에 적용하고 있는 상황이다. 해외의 연구사례를 살펴보면, 설계공식에 적용된 설계인자인 유속 및 수심 등을 1차원 단면평균값을 활용하는 경우가 많아서 복잡한 하천의 흐름특성을 반영하기에 미흡한 상황이다. 본 연구에서는 국내 하천해석에서 주로 활용되고 있는 수치모형을 이용하여 실험수로의 흐름을 재현하고 수리실험을 통하여 관측한 유속 및 수위분포 결과와 비교하였다. 2차원 수치모형으로는 RMA2, CCHE2D, FLUMEN 등의 상용모형과 최근 연구가 활발히 진행되고 있는 Approximate Riemann 기법을 적용하여 개발된 유한체적모형을 적용하였다. 제방 부근에서 형성되는 흐름을 상세하게 모의하기 위하여 국내 하천시설물 설계에서 많이 활용되고 있는 FLOW-3D 모형을 적용하여 3차원 모의결과와 수리실험결과를 비교하였다. 수리실험에서 관측된 사석호안공의 이탈시 흐름현상을 재현하여 호안공 이탈에 영향을 미치는 국부유속 및 전단응력을 산정하여 호안설계에 적합한 설계인자를 분석하였다. 연구결과를 활용하여 사석호안공 설계 기법에 적용되는 수치모형을 통하여 산정되는 설계인자의 정확성을 향상시킴으로써, 정량적이고 합리적인 사석호안공 설계기법개발에 도움이 될 것으로 판단된다.

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A Development of 3-D Numeric Model for the Confined Flow and Discharge under Sea Ground (해저 지중 피압유체의 흐름과 양수량 산출에 관한 3차원 수치모형의 개발)

  • Kim, Sang-Jun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.6
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    • pp.387-396
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    • 2010
  • A 3-D numeric model for the confined transient flow under sea ground have been developed. This is FDM model using Gauss-Seidel SOR (successive over-relaxation). This model shows the similar head distribution pattern to Theis analytic solution and MODFLOW simulation. The input flowrate to the aquifer and discharge of well have been compared. And it have been found that mass balance is influenced by the weight factor ${\alpha}$, i.e. fullyimplicit method (${\alpha}$=1) shows 5% error, but when ${\alpha}$ becomes to 0.5(Crank and Nicolson method) the mass balance becomes worse and the model result diverges. And the convergency of the model is not much different when $\lambda$ (over-relaxation factor)=0.8~1.5, but when $\lambda$>1.5, the model result diverges. The test-run shows that the well discharge becomes smaller when another well is near. This model can cover the isotropy$(Kx{\neq}Ky{\neq}Kz)$ and inhomogeneity, and can be used for the selection of well site, discharge calculation, and head prediction in case of the artificial recharge etc.

Uptake and Elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD) and 3,3 ,4,4 ,5-pentachlorobiphenyl(PCB126) in Japanese Medaka(Oryzias latipes) (일본송사리에서 TCDD 및 PCB 126의 흡수 및 배설)

  • 김영철
    • Journal of Environmental Health Sciences
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    • v.28 no.2
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    • pp.131-139
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    • 2002
  • 초기생애단계의 일본송사리를 실험어류로 사용하여 TCDD와 PCB 126의 생물농축정도를 비교 측정하였고, TCDD와 PCB 126의 체외 배설에 대한 동태학적 특성을 비교 분석하였다. 생물농축실험은 초기생애단계의 새끼치어 및 어린 물고기에 TCDD와 PCB 126을 여러 농도로 물에 용해시켜 96시간 동안 정체된 상태로 폭로시킨 후 생물농축계수(BCF)와 지방-표준화한 생물농축계수(BCF$_{L}$)를 측정하였다. TCDD와 PCB 126의 일본송사리 초기생애단계의 새끼치어 및 어린 물고기에서 측정된 96-h BCF값 및 96-h BCF$_{L}$값은 폭로된 농도와 상관없이 비슷하게 나타나 반면, 생체크기가 클수록 그 값은 작게 나타났다. 일본송사리 새끼치어, 어린 물고기, 성어의 생체 내 총 지방함량은 각각 5.7, 4.2, 4.6%로 측정되었다. 체외배설 동태실험은 어린 물고기에 TCDD와 PCB 126을 3가지 농도롤 물에 용해시켜 96시간 동안 정체된 상태로 폭로시킨 후, flow-through장치로 공급되는 맑은 물로 옮겨 42일간 사양하면서 0, 7, 14, 21, 28, 42일에 생체 내 TCDD와 PCB 126 잔류량을 측정하여 분석하였다. 배설은 1차 반응속도론적으로 이루어졌으며 한 구획모형보다 두 구획모형이 더 적합한 것으로 분석되었다. 두 구획모형을 사용한 분석에서 TCDD와 PCB 126의 체외배설 반감기(t$\frac{1}{2}$) 및 배설속도상수($\beta$)는 각각 27.2일과 32.3일 및 0.025/d와 0.021/d로 측정되었다.

The Optimal Operation on Auxiliary Spillway to Minimize the Flood Damage in Downstream River with Various Outflow Conditions (하류하천의 영향 최소화를 위한 보조 여수로 최적 활용방안 검토)

  • Yoo, Hyung Ju;Joo, Sung Sik;Kwon, Beom Jae;Lee, Seung Oh
    • Journal of Korean Society of Disaster and Security
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    • v.14 no.2
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    • pp.61-75
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    • 2021
  • Recently, as the occurrence frequency of sudden floods due to climate change increased and the aging of the existing spillway, it is necessary to establish a plan to utilize an auxiliary spillway to minimize the flood damage of downstream rivers. Most studies have been conducted on the review of flow characteristics according to the operation of auxiliary spillway through the hydraulic experiments and numerical modeling. However, the studies on examination of flood damage in the downstream rivers and the stability of the revetment according to the operation of the auxiliary spillway were relatively insufficient in the literature. In this study, the stability of the revetment on the downstream river according to the outflow conditions of the existing and auxiliary spillway was examined by using 3D numerical model, FLOW-3D. The velocity, water surface elevation and shear stress results of FLOW-3D were compared with the permissible velocity and shear stress of design criteria. It was assumed the sluice gate was fully opened. As a result of numerical simulations of various auxiliary spillway operations during flood season, the single operation of the auxiliary spillway showed the reduction effect of maximum velocity and the water surface elevation compared with the single operation of the existing spillway. The stability of the revetment on downstream was satisfied under the condition of outflow less than 45% of the design flood discharge. However, the potential overtopping damage was confirmed in the case of exceeding the 45% of the design flood discharge. Therefore, the simultaneous operation with the existing spillway was important to ensure the stability on design flood discharge condition. As a result of examining the allocation ratio and the total allowable outflow, the reduction effect of maximum velocity was confirmed on the condition, where the amount of outflow on auxiliary spillway was more than that on existing spillway. It is because the flow of downstream rivers was concentrated in the center due to the outflow of existing spillway. The permissible velocity and shear stress were satisfied under the condition of less than 77% of the design flood discharge with simultaneous operation. It was found that the flood damage of downstream rivers can be minimized by setting the amount allocated to the auxiliary spillway to be larger than the amount allocated to the existing spillway for the total outflow with simultaneous operation condition. However, this study only reviewed the flow characteristics around the revetment according to the outflow of spillway under the full opening of the sluice gate condition. Therefore, the various sluice opening conditions and outflow scenarios will be asked to derive more efficient utilization of the auxiliary spillway in th future.

A Study on the Hydraulic Stability and Efficiency Investigation of Water Purification Material Installed in Channel (수질정화체를 설치한 수로의 수리적 안정성과 효율성 연구)

  • Kang, Seung-Mook;Kim, Sun-Joo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2008.05a
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    • pp.650-654
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    • 2008
  • 친환경 공법의 수리적인 안전성 검토는 식생 및 자연재료의 물리적 특성, 하천의 수리 수문학적 특성, 유사특성과 이들의 상호관계 등에 대한 분석이 요구되며, 이에 선행하여 분석에 이용되는 장기간의 충분한 자료가 구축되어 있어야 한다. 그러나 우리나라의 경우 이러한 자료는 부족한 실정이며, 주로 시범구간을 통한 제한된 자료만이 이용되고 있을 뿐이므로 수리학적 치수방재적 측면에서 친환경 공법의 안전성 평가에 있어 많은 어려움을 겪고 있다. 본 연구에서 수질정화체의 배치 변화를 통한 수치해석 통하여 수심 및 유속분포를 비교 분석하여 수로의 3차원적 흐름특성을 파악하고, 실제 대상수로에 수질정화체를 설치하여 수로의 수리적 안정성을 연구하였다. FLOW-3D와 수리모형시험 그리고 대상수로 모니터링을 각 경우에 따라 유속, 수위를 측정하여 다양한 조건에 대한 흐름 특성을 연구하였다.

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