• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.35-41
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• 2020

We conduct numerical simulations of the interaction of a deformable structure with two-phase compressible flow. The finite volume method (FVM) is used to simulate fluid phenomena including a shock wave, a gas bubble, and the deformation of free surface. The deformation of a floating structure is computed with the finite element method (FEM). The compressible two-phase volume of fluid (VOF) method is used for the generation and development of a cavitation bubble, and the immersed boundary method (IBM) is used to impose the effect of the structure on the fluid domain. The result of the simulation shows the generation of a shock wave, and the expansion of the bubble. Also, the deformation of the structure due to the hydrodynamic loading by the explosion is identified.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.25-33
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• 1998

An experimental study has been carried out to obtain optimal conditions for turbulent mixing of two fluid streams at various angle branches by a flow visualization method. The main purpose of this study is the utilization of flow visualization method as a fast and efficient way to find the optimal mixing conditions when several flow control parameters are superimposed. It is verified that the optimal conditions estimated by flow visualization method have good agreement with the concentration field measurements. The results demonstrate that the diameter ratio is mainly attributed to the mixing phenomena than the branch pipe angle and the Reynolds number. The most striking fact is that there exists the best diameter ratio, d/D.ident. O.17, which requires the minimum momentum ratio in the range of the present experiment. The velocity ratio for the optimal mixing condition has a value within 2 to 16 according to the different flow parameters.

• Journal of the Korean Society of Visualization
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• v.16 no.2
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• pp.7-15
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• 2018

The fluid-flow characteristics of flue-gas-recirculation (FGR) system can have a significant effect on system efficiency of a sintering plant. The flow characteristics in the system were investigated. A sintering plant with FGR system was modeled. Numerical visualization was performed and flow characteristics were analyzed. Characteristics of the flow distribution of the branch ducts, the inflow of air into the recirculating hood, and the flow in the hood were discussed. Based on the results three suggestions were proposed: (1) distribution of branch duct flowrate upstream, (2) installation of external air ducts in the hood, and (3) installation of baffles at the hood corners. The suggestions were tested numerical and experimental visualization methods. The suggestions were effective and confirmed to be applicable to the actual sinter plant.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.162-168
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• 2001

In the present study, flow visualizations, hot-wire velocity measurements and computational fluid dynamics were performed in order to determine complicated air flow characteristics in a neonate incubator. In this study, following conclusions can be made: (1) The flow visualization technique developed in the present study revealed an enough qualitative information for the flow field in the neonate incubator. Flow structures in a neonate incubator with a realistic three-dimensional shape was successfully visualized the present study. (2) Results from the flow visualization were relatively in good agreements with those obtained from the computational fluid dynamics. (3) Velocities very near the neonate measured by the hot-wire anemometer were relevant to those obtained from the computational fluid dynamics. (4) Temperatures were higher at the neck region and the medial aspect of both thighs, but lower in both extremities. (5) Small vortices between the neonate and the mattress might interfere with convective and evaporative heat transfers on the neonate's surface. In the fluid dynamic aspect, it is important to eliminate the formation of these small vortices for the design of incubator chamber.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.46-52
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• 2001

SMAC method, one of the numerical simulation techniques, is modified from the original MAC method for the time-dependent variation of fluid flows. The Navier-Stokes equations for incompressible time-dependent viscous flow are applied, and Also marker particles which present the visualization of fluid flows are used. In this study, two-dimensional numerical simulations of the overtopping are carried out by SMAC method, and the simulation results are visualized, In addition to, motion pictures are made for efficient visualization of the simulation results. This numerical simulation could also be applied to the design of coastal structures as dike and revetment.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1794-1800
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• 2001

Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al. 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD and using the existing method.

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.57-63
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• 2004

various applications is presented. It is based on rapid-prototyping of transparent model for flow visualization and on the use of refractive index matching that enables efficient and clear visualization of the flow inside the model. The model is immersed in the index-matching fluid in a glass tank so that any displacement and rotation of the model in the tank have no influence on the optical setup for image acquisition to be made through a glass wall. This can facilitate greatly the camera calibration for stereo PIV and 3-D PTV. As the flow model is generated directly from 3-D surface data, no laborious preparation of the flow model is needed. This approach for seamless linking of model generation and PIV measurement is applicable to various flow measurements in automobile, ship building, fluid machinery, turbine, electrical appliances, heat exchanger, electronic cooling, bio-engineering and so on.

• Journal of the Korean Society of Visualization
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• v.15 no.2
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• pp.3-9
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• 2017

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2879-2884
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• 2007

Dynamic responses of electrorheological (ER) fluids in steady pressure flow to stepwise electric field excitations are investigated experimentally. The transient periods under various applied electric fields and flow velocities were determined from the pressure behavior of the ER fluid in the flow channel with two parallel-plate electrodes. The pressure response times were exponentially decreased with the increase of the flow velocity, but increased with the increase of the applied electric field strength. In order to investigate the cluster structure formation of the ER particles, it was verified using the flow visualization technique that the transient response of ER fluids in the flow mode is assigned to the densification process in the competition of the electric field-induced particle attractive interaction forces and the hydrodynamic forces, unlike that in the shear mode determined by the aggregation process.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.155-161
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• 2001

Fundamental studies on the drag reduction of the circular cylinder having dimple were conducted by the measurement of the fluid force acting on the cylinder and by the flow visualization around the cylinder. The drag coefficients were changed by the shape and the geometrical arrangement of the dimple. The drag of the cylinder was reduced about 25% by the proper arrangement of the dimple. The flow field around the cylinder having dimple, which was the minimum drag, was visualized by the hydrogen bubble technique. In this case, the separation points were moved rearward and the wake region was small in comparison with that of the cylinder having no dimple.