• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.159-165
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• 2006

Numerical simulation of turbulence flow in a circulating channel was performed. The RNG $k-\varepsilon$ model and Reynolds stress model of the FLUENT was used for evaluating the flow mechanisms. The simulation results were compared with the experimental data measured by a ADV (Acoustic Doppler Velocitmeter). The distribution of chironomids was analyzed by the computational results. They distributed at the region of lower velocities and lower turbulence intensity. In the case of a hemisphere structure being located on the straight section, chironomids lived in the upstream and downstream area of the hemisphere. The secondary currents also affected the distribution of chironomids. In conclusion, the computational fluid dynamic techniques can be inexpensively applied for analysing the relationship between flow characteristics and distribution of benthic macroinvertebrates.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.71-81
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• 2017

When an integral pressurized water reactor is operated under low power conditions, once-through steam generator group operation strategy is applied. However, group operation strategy will cause nonuniform coolant flow distribution at the core inlet and lower plenum. To help coolant flow mix more uniformly, a flow mixing chamber (FMC) has been designed. In this paper, computational fluid dynamics methods have been used to investigate the coolant distribution by the effect of FMC. Velocity and temperature characteristics under different low power conditions and optimized FMC configuration have been analyzed. The results illustrate that the FMC can help improve the nonuniform coolant temperature distribution at the core inlet effectively; at the same time, the FMC will induce more resistance in the downcomer and lower plenum.

• Journal of Ocean Engineering and Technology
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• v.25 no.4
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• pp.23-27
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• 2011

This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

• Water Engineering Research
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• v.1 no.4
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• pp.321-330
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• 2000

The grid-based KIneMatic wave STOrm Runoff Model(Kim, 1998; Kim, et al., 1998) which predicts temporal variation and spatial distribution of overland flow, subsurface flow and stream flow was evaluated at two watersheds. This model adopts the single overland flowpath algorithm and simulates surface and/or subsurface water depth at each cell by using water balance of hydrologic components. The model programmed by C-language uses ASCII-formatted map data supported by the irregular gridded map of the GRASS(Geographic Resources Analysis Support System) GIS and generates the spatial distribution maps of discharge, flow depth and soil moisture of the watershed.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.827-831
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• 2009

Recently, frequency occurring flood and drought has increased the necessity of an effective water resources control and management of river flows. Therefore, the simulation of the flow distribution in natural rivers is great importance to the solution of a wide variety of practical flow problems in water resources engineering. However The serious problem facing two-dimensional hydraulic model is the treatment of wet and dry areas. The objective of this study is to investigate the wet and dry parameters that have direct relevance to model performance in situations where inundation of initially dry areas occurs. Several numerical simulations were carried out, which examined the performance of the marsh porosity method for the purpose of sensitivity analysis. Experimental channel and a variety of channel were performed for model tests. The results were compared with those of the observation data and simulation data of existing model. The RMA-2 model displayed reasonable flow distribution compare to the observation data and simulation data of existing model in dry area for application of natural river flow. As a result of this study, effectively applied marsh porosity method provide a reliable results for flow distribution of wet and dry area, it could be further developed to basis for extending to water quality and sediment transport analysis.

• Solar Energy
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• v.19 no.3
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• pp.53-61
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• 1999

We already presented new calculation method about the temperature distribution in hot water pipe flow of the unsteady condition. In this paper, we introduce consequence of the case study to confirm appropriation of the calculation method, and case study performs to establish actual hot water use supposed two model that is; the CWV(constant water volume) and VWV(variable water volume).

• Proceedings of the Korea Water Resources Association Conference
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• 2000.05a
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• pp.20-27
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• 2000

The grid-based KlneMatic wave STOrm Runoff Modei (Kim, 1998; Kim, et al., 1998) which predicts temporal variation and spatial distribution of saturated overland flow, subsurface flow and stream flow was evaluated at two watersheds. This model adopts the single overland flowpath algorithm and simulates surface and/or subsurface water depth at each cell by using water balance of hydrologic components. The model programed by C-language uses ASCII-formatted map data supported by the irregular gridded map of the GRASS (Geographic Resources Analysis Support System) GIS and generates the spatial distribution maps of discharge, flow depth and soil moisture of the watershed.

• Journal of Korea Water Resources Association
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• v.33 no.S1
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• pp.20-27
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• 2000

The grid-based KIneMatic wave STOrm Runoff Model(Kim, 1998; Kim, et al., 1998) which predicts temporal variation and spatial distribution of saturated overland flow, subsurface flow and stream flow was evaluated at two watersheds. this model adopts the single overland flowpath algorithm and simulates surface and/or subsurface water depth at each cell by using water balance of hydrologic components. the model programmed by C-language uses ASCII-formatted map data supported by the irregular gridded map of the GRASS (Geographic Resources Analysis Support System) GIS and generates the spatial distribution maps of discharge, flow depth and soil moisture of the watershed.

• Water Engineering Research
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• v.3 no.2
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• pp.135-142
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• 2002

This study investigates the effects of sediment on the flow characteristics such as velocity distribution, friction velocity, turbulent intensities, Reynolds stress, etc. Particle tracking velocimetry (PTY) is used to measure the vertical flow field. Results show that flow over the high bed-load concentration region has larger values of mean velocity and friction velocity and smaller values of turbulence intensities, compared to those for flow over the low bed-load concentration region.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.4
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• pp.441-451
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• 2014

The flushing is important to maintain good water quality in water main. It is a technique of using water velocity to remove sediments in water distribution system. The variety of water quality problems can occur in a distribution system, so too can a variety of benefits be gained by system flushing. In order to effectively perform the flushing, the contaminants to be removed to set up and it can be solved, it is necessary to ensure the proper flow rate. In this study, the removal of contaminants present in the inner water pipe attached loose deposits such as fine particles of granular activated carbon, sand and iron corrosion product sought to derive flow rates. Thus, the constant observation of using pilot plant scale water distribution plant for the movement of floating characteristics of particles were assessed.