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제안 방법
- Finally, this study found the flood inundation depth according to the levee-breach into the horizontal inundation area., and the measured water depth was compared with the results of the two-dimensional numerical solver that was developed in this study.
- Yoon (2008) performed the levee-breach experiments for various breach types in which vertical and trapezoidal shapes. But, in this study to simplify the experimental and numerical modeling, two levee-breach cases, such as the vertical abrupt and vertical gradual levee-breach types, were selected. Also, the initial velocity of the channel was assumed to be zero and the flow direction in the reservoir after levee-breach is symmetric against the flow direction at the center of the levee-breach.
- In the numerical approaches, two-dimensional shallow water solver including the effects of horizontal turbulence was developed. Finally, the developed numerical model was applied to the experiments of this study, and its accuracy was verified by comparing with experimental measurements. The numerical simulations developed in this study showed good agreement with the experimental data.
- The numerical simulations developed in this study showed good agreement with the experimental data. However, there were a little difference for the location and height of the hydraulic jump, even if the model considers the Smagorinsky horizontal eddy viscosity. This shows the shallow water equation solver has a limitation to reproduce the energy dissipation due to the hydraulic jump.
- In this study, abrupt and gradual levee-breach problems were analyzed by laboratory experiments and numerical simulations. In the experimental approaches, the characteristics of the abrupt and gradual levee-breach flow for some experimental conditions were studied.
- Roughness coefficient is very important factor to analyze a flow of river or inundation area. In this study, the time histories of the computed water depth from the first-order scheme for each gauge were compared with measured water depths for the some roughness coefficient and Smagorinsky coefficients. The optimum roughness coefficient was determined with 0.
- They carried out laboratory dam-break experiments using a rectangular upstream reservoir connected to a 90° and 45° bend open channel.
- Frazão and Zech (2008) studied a sudden flow of the dam-break wave type in an idealized city. They focused on the severe transient phase of such flows, with the aim of making available a complete data set with accurate flow depth and velocity measurements, allowing for the validation of numerical models. Yoon (2008) developed a sliding gate system that can open gradually to simulate a gradual levee-break on the inundation area.
- Finally, he found a various characteristics of the levee-break flow. This study was performed in a large scale model to obtain the accuracy of the experiment, and tested on the flat inundation area large enough to avoid the reflective wave and friction of the wall by Kim(2010). In order to effectively measure the flood depth, advanced ultrasonic distance sensors (UDS) were used instead of the resistive level gauges which are normally used in the hydraulic laboratory.
대상 데이터
- Each failure type has three cases in accordance with no block, block and its rotation angle. The test area is 30 m by 30 m with a horizontal concrete bed, and the experimental domain is divided into the reservoir and inundation area by the vertical concrete wall as shown in Fig. 1. To reproduce the levee-breach of the concrete wall, two types of gates were set up on the center of the wall.
이론/모형
- Turbulence may be defined generally as the effect of temporal variations in velocity, and the momentum exchange associated with their spatial gradient. In order to consider turbulence the Smagorinsky (1963) coefficient was adopted for the horizontal eddy viscosity. # is expressed with Eq.
- In this study, the two-dimensional numerical solver to calculate the gradual and abrupt dam or levee-breach problems was developed. The governing equations of the model are two- dimensional nonlinear shallow water equations and discretized explicitly by using a finite volume method (FVM). An intercell flux is reconstructed with a HLLC approximate Riemann solver which is a modification of the basic HLL scheme to account for the influence of intermediate waves.
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