• Title, Summary, Keyword: Numerical Model

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Analysis of Hydraulic Characteristics in the Middle Reaches of Nak-Dong River using 2-Dimensional Numerical Analyis Model (2차원 수치해석모형을 이용한 낙동강 중류구간의 하천흐름 해석)

  • Han, Sung-Dea;Choi, Hyun;Ahn, Chang-Hwan;Lee, Je-Yun
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.1732-1736
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    • 2008
  • The characteristics of a river flow analysis are significant for river maintenance plan. At the present time, HEC-RAS, 1-Dimensional Numerical Analysis Model, is mainly applied to analyze the character of a river flow. The shape of a river is somewhat in longitudinal linear form. It was suspected that the usage of 1-dimensional numerical analysis model is more economical. Development of numerical analysis models and computers are possible to calculate large volume. Hence, it is possible to adapt the analysis of the key stations by 2-dimensional numerical analysis model. The limitation of 1-Dimensional Numerical Analysis Model is that it is hard to evaluate structure affection of numerical simulation by energy loss coefficient at river structure analyzing. When adaptation of the 2-dimensional numerical analysis model in river structure ensues, it takes more objective analyzing than 1-dimensional numerical analysis model for flow affection by river structure. 2-dimensional numerical analysis model consults with the different structure position of hydraulic characteristics and different water depth of shape and scope in vertical flow. 1-dimensional numerical analysis model is possible to simulate with only energy loss coefficient for sudden river section changing, sudden waterway changing by curved. 2-dimensional numerical analysis model use original geographical features. So the model removes technical subjectivity of faulty judgment. It is an objective analysis.

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A Comparative Study on Hydraulic Characteristics of Curved Channel by Hydraulic Model Experiments and Numerical Analysis (수리모형과 수치해석을 통한 만곡부 하천의 수리학적 특성 비교 고찰)

  • Seo, Dong-Il;Choi, Han-Kuy
    • Journal of Industrial Technology
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    • v.27 no.A
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    • pp.85-94
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    • 2007
  • This study, regarding curved channel, was performed to compare and analyze hydraulic characteristics and the speed of water and water level for left bank and right bank through hydraulic model experiments and numerical analysis. Real channels that had characteristics of curved channel were selected as objectives. In order to easily operate one and two dimensional numerical analysis and comparison for total 2.4Km model channel, measuring point was set up as 200m. HEC-RAS model was applied as one dimensional numerical analysis program and SMS model was used as two dimensional numerical analysis program. In respect of speed of water, the average speed of water for right bank recorded 8.33m/s in a model experiment and 3.08m/s, 8.57m/s were average speed of water for right bank in one dimensional and two dimensional numerical analysis. The average speed of water of two dimensional numerical analysis was quite similar to that of model experiments. Also, as for water level, maximum observational errors between one and two dimensional numerical analysis for right and left bank of model experiments were 0.66m, 0.84m and 0.28m, 0.48m for each. It was found that two dimensional numerical analysis had a similar result to hydraulic model experiments. Accordingly, from the result of this study, two dimensional numerical analysis should be used rather than one dimensional numerical analysis, when numerical analysis for curved channel is conducted.

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유선 시뮬레이션 기법과 준해석해를 이용한 용질 거동 분석

  • 정대인;최종근;박광원
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.57-62
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    • 2004
  • Streamline simulation researches have been extensively accomplished due to the swiftness of computation and the reduction of numerical dispersion. In this study, we developed a streamline simulation model using a semianalytical solution of ID transport equation. To validate accuracy of the developed model, we compared simulation results of contaminant transport, which were acquired by streamline simulation models using an analytical solution, a numerical solution, and a semianalytical solution. The developed model using the semianalytical solution matched well with the model using an analytical solution. However, streamline simulation model using a numerical solution showed numerical dispersion. For an advection-dominant flow, there was little difference in the simulation results between the developed model and tile analytical model, but the differences between the analytical model and the numerical model were cleary shown. From the comparison of computing time we know that the streamline simulation using the semianalytical solution is 2-60 times as fast as the streamline simulation using the numerical solution.

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Numerical Solutio of Inverse Problem of Fuzzy Modeling with Pseudo First Order Approzimation

  • Ikoma, Norikazu;Hirota, Kaoru
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.1230-1233
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    • 1993
  • Numerical solution of inverse problem of Takagi-Sugeno fuzzy model is proposed. The method is located on the application of numerical optimization to the fuzzy model. Steepest descent method is used for the numerical optimization. We use the linear approximation of fuzzy model, called pseudo first order approximation, by fixing the membership value on the neighborhood of the corresponding input. It is introduced in order to reduce the difficulty of optimization process. The efficiency of this method is shown by a numerical experiment.

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DEVELOPMENT OF EULERIAN-GRANULAR MODEL FOR NUMERICAL SIMULATION MODEL OF PARTICULATE FLOW (Eulerian-Granular method를 사용한 고체 입자 유동 모델 개발)

  • Lee, T.G.;Shin, S.W.
    • Journal of computational fluids engineering
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    • v.20 no.2
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    • pp.46-51
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    • 2015
  • In this paper, we have developed numerical model for particulated flow through narrow slit using Eulerian-Granular method. Commercial software (FLUENT) was utilized as simulation tool and main focus was to identify the effect from various numerical options for modeling of solid particles as continuos phase in granular flow. Gidaspow model was chosen as basic model for solid viscosity and drag model. And lun-et-al model was used as solid pressure and radial distribution model, respectively. Several other model options in FLUENT were tested considering the cross related effect. Mass flow rate of the particulate through the slit was measured to compare. Due to the high volume density of the stacked particulates above the slit, effect from various numerical options were not significant. The numerical results from basic model were also compared with experimental results and showed very good agreement. The effects from the characteristics of particles such as diameter, angle of internal friction, and collision coefficient were also analyzed for future design of velocity resistance layer in solar thermal absorber. Angle of internal friction was found to be the dominat variable for the particle mass flow rate considerably. More defined 3D model along with energy equation for complete solar thermal absorber design is currently underway.

Development of Numerical Model for Scour Analysis under Wave Loads in Front of an Impermeable Submerged Breakwater (불투과 잠제 전면에서 파랑 작용 하의 세굴 해석을 위한 수치모델의 개발)

  • Hur, Dong-Soo;Jeon, Ho-Seong
    • Journal of The Korean Society of Civil Engineers
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    • v.31 no.5B
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    • pp.483-489
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    • 2011
  • In this study, the coupled-numerical model has been newly developed to investigate numerically scouring and deposition around a coastal structure like a submerged breakwater using a numerical wave model and a lagrangian particle model for sand transport. As a numerical wave model, LES-WASS-2D (Hur and Choi, 2008) is adopted. The model is able to consider the flow through a porous midium with inertial, laminar and turbulent resistance term and determine the eddy viscosity with LES turbulence model. Distinct element method (Cundall and Strack, 1979), which is able to apply to many dynamical analysis of particulate media, as a lagrangian particle model for sand transport is newly coupled to the numerical wave model. The numerical simulation has been carried out to examine the scour problem in front of an impermeable submerged breakwater using the newly coupled-numerical model. The numerical results has been compared qualitatively with an existing experimental data and then its applicability has been discussed.

Two-Dimensional Numerical Simulation of Saltwater intrusion in Estuary with Sigma-Coordinate Transformation (연직좌표변환을 이용한 하구에서의 염수침투에 관한 2차원 수치모의)

  • Bae, Yong-Hoon;Park, Seong-Soo;Lee, Seung-Oh;Cho, Yong-Sik
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.1263-1267
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    • 2007
  • A more complete two-dimensional vertical numerical model has been developed to describe the saltwater intrusion in an estuary. The model is based on the previous studies in order to obtain a better accuracy. The non-linear terms of the governing equations are analyzed and the $\sigma$-coordinate system is employed in the vertical direction with full transformation which is recently issued in several studies because numerical errors can be generated during the coordinate transformation of the diffusion term. The advection terms of the governing equations are discretized by an upwind scheme in second-order of accuracy. By employing an explicit scheme for the longitudinal direction and an implicit scheme for the vertical direction, the numerical model is free from the restriction of temporal step size caused by a relatively small grid ratio. In previous researches, some terms induced from the transformation have been intentionally excluded since they are asked the complicate discretization of the numerical model. However, the lack of these terms introduces significant errors during the numerical simulation of scalar transport problems, such as saltwater intrusion and sediment transport in an estuary. The numerical accuracy attributable to the full transformation is verified by comparing results with a previous model in a simply sloped topography. The numerical model is applied to the Han River estuary. Very reasonable agreements for salinity intrusion are observed.

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Development of an Accurate Numerical Model for Density-Dependent Groundwater Flow and Solute Transport (밀도가 변하는 지하수흐름과 용질의 수송을 위한 정확한 수치모델의 개발)

  • Park, Nam-Sik
    • Journal of Korea Water Resources Association
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    • v.30 no.6
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    • pp.753-759
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    • 1997
  • A new numerical model was doveloped to simulate density-dependent ground water flow and solute transport. Accuracy of a numerical model depends upon how well it simulates advection dominant situations because numerical oscillations can spoil solutions for these situations. Nonlinear oscillation-absorption finite element method. based on the variational principle, was employed. Unlike previous numerical models, this model can easily be expanded for more complex situations. Accuracy of the model is evaluated by comparing with analytical solutions and results of other numerical model.

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The behaviour of structures under fire - numerical model with experimental verification

  • Toric, Neno;Harapin, Alen;Boko, Ivica
    • Steel and Composite Structures
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    • v.15 no.3
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    • pp.247-266
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    • 2013
  • This paper presents a comparison of results obtained by a newly developed numerical model for predicting the behaviour of structures under fire with experimental study carried out on heated and simply supported steel beam elements. A newly developed numerical model consists of three submodels: 3D beam model designed for calculating the inner forces in the structure, 2D model designed for calculation of stress and strain distribution over the cross section, including the section stiffness, and 3D transient nonlinear heat transfer model that is capable of calculating the temperature distribution along the structure, and the distribution over the cross section as well. Predictions of the calculated temperatures and vertical deflections obtained by the numerical model are compared with the results of the inhouse experiment in which steel beam element under load was heated for 90 minutes.

Numerical model for nonlinear analysis of composite concrete-steel-masonry bridges

  • Baloevic, Goran;Radnic, Jure;Grgic, Nikola;Matesan, Domagoj;Smilovic, Marija
    • Coupled systems mechanics
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    • v.5 no.1
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    • pp.1-20
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    • 2016
  • This paper firstly briefly describes developed numerical model for both static and dynamic analysis of planar structures made of concrete, steel and masonry. The model can simulate the main nonlinearity of such individual and composite structures. The model is quite simple and based on a small number of material parameters. After that, three real composite concrete-steel-masonry bridges were analyzed using the presented numerical model. It was concluded that the model can be useful in practical analysis of composite bridges. However, future verifications of the presented numerical model are desirable.