• 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.

• Structural Engineering and Mechanics
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• v.33 no.5
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• pp.621-633
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• 2009

In this paper we compare the solution of the one-dimensional beam model and the numerical solution of the two-dimensional linearized elasticity problem for rectangular domain of the beam-like form. We first derive the beam model starting from the two-dimensional linearized elasticity, the same way it is derived from the three-dimensional linearized elasticity. Then we present the numerical solution of the two-dimensional problem by finite element method. As expected the difference of two approximations becomes smaller as the thickness of the beam tends to zero. We then analyze the applicability of the one-dimensional model and verify the main properties of the beam modeling for thin beams.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1321-1326
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• 2002

A numerical model is investigated to predict a behavior of the gaseous volatile organic compounds and a subsurface contamination caused by them in the unsaturated zone. Two dimensional advective-dispersion equation caused by a density difference and two dimensional diffusion equation are computed by a finite difference method in the numerical model. A laboratory experiment is also carried out to compare the results of the numerical model. The dimensions of the experimental plume are 1.2m in length, 0.5m in height, and 0.05m in thickness. In comparing the result of 2 methods used in the numerical model with the one of the experiment respectively, the one of the advective-dispersion equation shows better than the one the diffusion equation.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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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.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.193-198
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• 2008

When the existing polder levee was constructed, the river's numerical analysis decided the bank raise by applying the planned flood stage or by using the result from the sectional 1st dimensional numerical analysis. But, it was presented that there is a limitation in the 1st dimensional value analysis when the structure like the polder levee obstructs the special shaped running water flow. Therefore, in order to verify the numerical value applicability when the polder levee is constructed, this report compared each other through the 1st and 2nd dimensional numerical analysis and the mathematical principle model laboratory. In case of the polder levee construction through the numerical analysis and the mathematical principle model laboratory, it was decided that there was no big problem in the 1st dimensional numerical analysis applied design, considering the uncertainty of mathematical principle analysis though the first dimensional numerical analysis was calculated a little bigger than the second. But, after construction, it was found that the water level deviation of the 1st, 2nd occurred biggest at the place where the flow was divided into two. Also, as a result of comparing the 1st, 2nd dimensional numerical analysis with the mathematical principle model laboratory, it was confirmed that the 1st numerical analysis applied design decreased the modal safety largely, as the left side water level was calculated smaller more than 0.5m in case of the 1st dimensional numerical analysis.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.129-137
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• 2006

In this research, we made a one and two-dimensional analysis of numerical data collected from the bend curvature of a bended river section. According to the result from the numerical analysis, the inflow ＆ output angle caused a water level deviation which increased with an increase of the flood discharge. From the water level deviation of our two-dimensional numerical model, we obtained the maximum slope of 6,67% when the inflow and output angle was 105 degrees and the flood discharge was 500 CMS. As for the right side, the differences with the one-dimensional numerical model were reduced when the angle was more than $90^{\circ}$. As for the left side the differences were reduced when the angle was more than $105^{\circ}$. For a river with more than 90 degrees bend curvature, a hydraulic experiment would be more appropriate than a numerical analysis.

• Nuclear Engineering and Technology
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• v.42 no.3
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• pp.279-296
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• 2010

For the analysis of transient two-phase flows in nuclear reactor components, a three-dimensional thermal hydraulics code, named CUPID, has been developed. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations were solved over unstructured grids, which are very useful for the analysis of flows in complicated geometries. To obtain numerical solutions, the semi-implicit numerical method for the REALP5 code was modified for an application to unstructured grids, and it has been further improved for enhanced accuracy and fast running. For the verification of the CUPID code, a set of conceptual problems and experiments were simulated. This paper presents the flow model, the numerical solution method, and the results of the preliminary assessment.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.237-240
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• 2008

Numerical Analysis for exchanging seawater experiment is carried out in Do-Jang fish port. The change of tidal velocity and water level is derived by the two-dimensional nonlinear shallow-water numerical model. To calculate exchange rate of seawater with the change of tidal velocity and water level, a two-dimensional numerical model is employed which governing equations are Fokker-Plank equations. The calculated exchange rates of each time are described in tables and figures.

• Computers and Concrete
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• v.34 no.2
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• pp.169-178
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• 2024

To circumvent the constraints of time-consuming experimental methods, numerical simulation can be one of the most effective approaches to investigating chloride diffusion behaviors in concrete. However, except for the effect of the external environments, the transport direction of the chloride cannot be neglected when the concrete is exposed to the marine tidal zone, especially in certain areas of concrete members. In this study, based on Fick's second law, considering the effects of timevarying, chloride binding capacity, concrete stress state, ambient temperature, and relative humidity on chloride diffusion coefficient, the modified one-dimensional, two-dimensional, and three-dimensional novel modified chloride diffusion theoretical models were established through defining the current boundary conditions. The simulated results based on the novel modified multi-dimensional model were compared with the experimental results obtained from some previous pieces of literature. The comparing results showed that the modified multi-dimensional model was well-fitted with experimental data, confirming the high accuracy of the novel modified model. The experimental results in literature showed that the chloride diffusion in the corner area of the concrete structure cannot be simulated by a simple one-dimensional diffusion model, where it is necessary to select a suitable multi-dimensional chloride diffusion model for simulation calculation. Therefore, the novel modified multi-dimensional model established in this study has a stronger applicability for practical engineering.

• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.52-57
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• 2002

A numerical investigation using a commercial CFD program of the Inter-Phase Slip Algorithm has been carried out for detail characteristics of particle motions and bubble behaviors in a two dimensional fluidized bed. The bed simulated has been operated with three different distributor geometries, such as bubble cap, nozzle, and perforated plate types. Experiments using a slit-type two-dimensional fluidized bed and a cylinder-type fluidized bed have been performed in order to confirm the simulation model. In addition, the numerical results are compared with the wellknown correlation of bubble sizes and bubble rising velocities by Mori and Wen [1]. The simulation model that we applied is shown to be useful to understand the relation between bubble behaviors and distributor geometries.