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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Water Resources Association
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Korea Water Resources Association
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Volume & Issues
Volume 44, Issue 12 - Dec 2011
Volume 44, Issue 11 - Nov 2011
Volume 44, Issue 10 - Oct 2011
Volume 44, Issue 9 - Sep 2011
Volume 44, Issue 8 - Aug 2011
Volume 44, Issue 7 - Jul 2011
Volume 44, Issue 6 - Jun 2011
Volume 44, Issue 5 - May 2011
Volume 44, Issue 4 - Apr 2011
Volume 44, Issue 3 - Mar 2011
Volume 44, Issue 2 - Feb 2011
Volume 44, Issue 1 - Jan 2011
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Free Surface Flow in a Trench Channel Using 3-D Finite Volume Method
Lee, Kil-Seong ; Park, Ki-Doo ; Oh, Jin-Ho ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 429~438
DOI : 10.3741/JKWRA.2011.44.6.429
In order to simulate a free surface flow in a trench channel, a three-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (RANS) equations are closed with the
model. The artificial compressibility (AC) method is used. Because the pressure fields can be coupled directly with the velocity fields, the incompressible Navier-Stokes (INS) equations can be solved for the unknown variables such as velocity components and pressure. The governing equations are discretized in a conservation form using a second order accurate finite volume method on non-staggered grids. In order to prevent the oscillatory behavior of computed solutions known as odd-even decoupling, an artificial dissipation using the flux-difference splitting upwind scheme is applied. To enhance the efficiency and robustness of the numerical algorithm, the implicit method of the Beam and Warming method is employed. The treatment of the free surface, so-called interface-tracking method, is proposed using the free surface evolution equation and the kinematic free surface boundary conditions at the free surface instead of the dynamic free surface boundary condition. AC method in this paper can be applied only to the hydrodynamic pressure using the decomposition into hydrostatic pressure and hydrodynamic pressure components. In this study, the boundary-fitted grids are used and advanced each time the free surface moved. The accuracy of our RANS solver is compared with the laboratory experimental and numerical data for a fully turbulent shallow-water trench flow. The algorithm yields practically identical velocity profiles that are in good overall agreement with the laboratory experimental measurement for the turbulent flow.
Application of EFDC and WASP7 in Series for Water Quality Modeling of the Yongdam Lake, Korea
Seo, Dong-Il ; Kim, Min-Ae ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 439~447
DOI : 10.3741/JKWRA.2011.44.6.439
This study aims to test the feasibility of combined use of EFDC (Environmental Fluid Dynamics Code) hydrodynamic model and WASP7.3 (Water Quality Analysis Program) model to improve accuracy of water quality predictions of the Yongdam Lake, Korea. The orthogonal curvilinear grid system was used for EFDC model to represent riverine shape of the study area. Relationship between volume, surface and elevation results were checked to verify if the grid system represents morphology of the lake properly. Monthly average boundary water quality conditions were estimated using the monthly monitored water quality data from Korean Ministry of Environment DB system. Monthly tributary flow rates were back-routed using dam discharge data and allocated in proportion to each basin area as direct measurements were not available. The optimum number of grid system was determined to be 372 horizontal cells and 10 vertical layers of the site for 1 year simulation of hydrodynamics and water quality out of iterative trials. Monthly observed BOD, TN, TP and Chl-a concentrations inside the lake were used for calibration of WASP7.3 model. This study shows that EFDC and WASP can be used in series successfully to improve accuracy in water quality modeling. However, it was observed that the amount of data to develop inflow water quality and flow rate boundary conditions and water quality data inside lake for calibration were not enough for accurate modeling. It is suggested that object-oriented data collection systems would be necessary to ensure accuracy of EFDC-WASP model application and thus for efficient lake water quality management strategy development.
Experimental Formulae Development of Hydraulic Stability for Riprap
Choi, Heung-Sik ; Park, Gwang-Ho ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 449~459
DOI : 10.3741/JKWRA.2011.44.6.449
By examining the experimental results, the critical mean velocity which initiates the movement of riprap is increased with the riprap size in mean diameter, the mean diameter over water depth (d/h), Froude number (Fr), and turbulent shear velocity over critical mean velocity (u*/
) which have great correlations among them so these parameters are adopted governing hydraulic stability for riprap. The hydraulic stability equation for riprap is developed by regression analysis. The developed equation is expanded from 0.36~0.73 m/s of experimental range to 0~5.0 m/s for the application in engineering discipline. So many useful relations among those parameters including critical mean velocity are derived by expanding to high Reynolds regions. Mean diameter calculation results by expanding to high Reynolds regions coincide with the calculations of ASCE and USBR at the range of 0~3.0 m/s and the calculation result of ASCE at the range of 3.0~5.0 m/s. The results by developed formulae coincide well with the formulae of ASCE in general and also the results by recently developed existing formulae of hydraulic stability for riprap. Thus, the developed equation has the high applicability in engineering discipline to evaluate the hydraulic stability for riprap.
Levee Breach Flow by Experiment and Numerical Simulation
Kim, Joo-Young ; Lee, Jong-Kyu ; Lee, Jin-Woo ; Cho, Yong-Sik ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 461~470
DOI : 10.3741/JKWRA.2011.44.6.461
Abrupt and gradual levee breach analyses on the flat domain were implemented by laboratory experiments and numerical simulations. To avoid the reflective wave from the side wall the experiment was performed in a large domain surrounded by waterway. A numerical model was developed for solving the two-dimensional gradual levee breach flow. The results of the numerical simulation developed in this study showed good agreement with those of the experimental data. However, even if the numerical schemes effectively replicated the trends of the observed water depth for the first shock, there were little differences for the second shock. In addition, even though the model considered the Smagorinsky horizontal eddy viscosity, the location and height of the hydraulic jump in the numerical simulation were not fairly well agree with experimental measurements. This shows the shallow water equation solver has a limitation which does not exactly reproduce the energy dissipation from the hydraulic jump. Further study might be required, considering the energy dissipation due to the hydraulic jump or transition flow from reflective wave.
Modified Scheme for Tsunami Propagation with Variable Water Depths
Ha, Tae-Min ; Seo, Kyu-Hak ; Kim, Ji-Hun ; Cho, Yong-Sik ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 471~476
DOI : 10.3741/JKWRA.2011.44.6.471
In this study, a modified dispersion-correction scheme describing tsunami propagation on variable water depths is proposed by introducing additional terms to the previous numerical scheme. The governing equations used in previous tsunami propagation models are slightly modified to consider the effects of a bottom slope. The numerical dispersion of the proposed model replaces the physical dispersion of the governing equations. Then, the modified scheme is employed to simulate tsunami propagation on variable water depths and numerical results are compared with those of the previous tsunami propagation model.
The Effect and Application of Flow Induction Machine in Artificial Canal Way and Lake through Water Quality Model Test
Choi, Gye-Woon ; Kim, Dong-Eon ; Yoon, Geun-Ho ; Han, Man-Shin ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 477~486
DOI : 10.3741/JKWRA.2011.44.6.477
The objective of this study is to investigate the water pollution problems brought about by the construction of eco-friendly waterfront space through the physical model experiment including water quality consideration. Due to the lack of water supply into the artificial ponds and canals, the water quality problems such as eutrophication, odor and so on can be occurred. There have been many numerical models on such phenomena but limited studies using physical test due to the difficulty in the verification of physical interpretation of the study area. In this study, a prototype model that is not affected by the dimensionless parameters was carried out, where unpolluted water is mixed into the contaminated water to reduce the concentration of nutrients. In addition, this study also attempt to find the optimal configuration of the flow induction machines using the scale model which will evaluate and verify the effectiveness of the enforcement methods to maintain the water quality objectives.
Analysis of the Erosion Characteristics with Root Fiber of a Vegetated Levee Revetment
Choi, Hueng-Sik ; Lee, Woong-Hee ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 487~495
DOI : 10.3741/JKWRA.2011.44.6.487
The sampling and measuring methods of root fiber quantity which greatly governs the stability evaluation of a vegetated levee revetment are proposed by this study and the erosion characteristics related to root fiber quantity are analysed by the experiments. The Phragmites Japonica Steud confirmed the dominant species in a vegetated levee revetment and the Zoysinagrass are selected as the experimental vegetations. The characteristics of erosion depth and erosion rate are analysed according to the root fiber quantity and their corresponding regression equations are suggested. The erosion depth and erosion rate highly decrease with root fiber quantity by experimental results which results in great increasing the erosion resistance of a vegetated levee revetment. The corresponding regression equations for both vegetations of the Phragmites Japonica Steud and the Zoysinagrass are suggested with high determination coefficients. The erosion resistance of the Zoysinagrass is better than that of the Phragmites Japonica Steud.
A Comparison and Analysis of the Levee Height Determination Methods in Korea and the USA
Kang, Tae-Uk ; Lee, Sang-Ho ; Yu, Kwon-Kyu ;
Journal of Korea Water Resources Association, volume 44, issue 6, 2011, Pages 497~510
DOI : 10.3741/JKWRA.2011.44.6.497
A levee height is determined by adding a deterministic freeboard to a flood water level in Korea. In the USA, a levee height is determined by choosing a value conditionally among the freeboard criteria and the levels resulted from a probabilistic method. The probabilistic method adopts a conditional non-exceedance probability (CNP) which is the probability that the target stage will not be exceeded given a specific flood event. The purpose of the study is to compare Korean criterion for levee height estimation with that of the USA. Levee heights were determined according to the above two criteria at twenty-five cross sections in five streams. The results show that Korean criterion on average yields levee heights 20 cm higher than those calculated by the criterion of the USA. The larger the flood discharges become, the higher the levee height differences are usually. It is caused by the freeboard estimation criterion of Korea that the larger design flood is, the higher freeboard is given. Korean criterion, however, resulted in lower levee heights for smaller streams than those by the criterion of the USA. To sum it up, the Korean levee height criteria can result in overestimation or underestimation depending on flood discharge amount, being compared with the criteria of the USA. The Korean freeboard especially needs to be increased for smaller flood discharges.