• Journal of the Korean Society of Visualization
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• v.11 no.2
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• pp.12-17
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• 2013

A flow visualization technique was developed to analyze flow distribution inside a dishwasher in this study. Then, a new design plan was proposed to improve the efficiency of the dishwasher by the analyzed results and it was confirmed experimentally by the developed technique. Gas flow fields inside a drying duct of a tub for a drying process was investigated by a developed PIV (Particle Image Velocimetry) and a CFD (Computational Fluid Dynamics) method. Also, the flow visualization technique was developed for the liquid flow field of a rotor-arm system to propose the improved design idea. Also, interactions between liquid and gas were observed around the rotor-arm system. The two-phase flow was modified to the liquid flow field because laser sheets are refracted when pass through the two-phase flow. Thus, the flow visualization techniques was developed in this study to measure the instantaneous flow velocities in the liquid quantitatively.

• Journal of the Korean Society of Visualization
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• v.8 no.3
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• pp.12-21
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• 2010

Swirling flows are found in very wide range of applications, for examples, cyclone separators, spraying machines, heat exchangers and jet pumps, ect. Relatively, little work has been done on the swirl flow using flow visualization techniques. This study deals with many visualization techniques to study on swirling flow. These techniques are related to oil films methods, smoke, dye liquids, liquid crystal, stroboscope light, smoke wire, white light, naphthalene sublimation, LDV(lase doppler Velocimetry) and PIV(particle image velocimetry). The present work has handled single, annular, carved tube, swirl expansion and swirl wake using several visualization methods in the vertical and horizontal circular tube.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.44-50
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• 2011

In this study, we propose a method for characterizing fluid-mechanical properties of a fluid surface, such as surface dilatational and shear viscosity, by matching the flow visualization and the numerical simulation for a Stokes flow in a three-dimensional cavity. The surface flow is driven by shear stress exerted on the free surface by an external gas flow. The external gas flow is simulated by using a commercial code, while the Stokes flow is calculated by an in-house code. We have found that the surface flow is very sensitive to the surface tension and other properties. The qualitative feature of the surface flow can be reproduced by the parameter tuning.

• Journal of the Korean Society of Visualization
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• v.1 no.1
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• pp.28-33
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• 2003

This paper presents the visualization method in which 3-dimensional(3D) microchannel flow can be detected using a confocal scanning microscope. By soft-lithography, we fabricated various Bio-MEMS(Micro Electro-Mechanical System) devices such as a disposable microchip for a flow cytometer and a micro-mixer, which have 3D structures. Injecting aqueous fluorescent solution in the microfluidic devices, we measured the flow in a steady state by the confocal scanning microscope. At first, we explain the principle of the confocal scanning microscope. And then we show the results from 3D visualization of microscopic flow structures using the confocal scanning microscope.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.3-5
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• 2006

Recently, the next-generation advanced flow visualization techniques such as holographic PIV, aynni.c PIV, echo-PIV, micro/nano-PIV, and X-ray PIV have been introduced. These advanced mea-surement techniques have a big potential as the core technology for analyzing outmost thermo-fluid flows in future. They would be indispensable in solving complicated thermo-fluid flow problems not only in industrial fields such as automotive, space, electronics, aero- and hydro-dynamics. steel, and information engineering, but also in the research fields of medical science, bio-medical engineering, environmental and energy technology etc. Especially, NT (Nano Technology) and BT (Bio Technology) strongly demand these advanced measurement techniques, because it is impossible for conventional measurement methods to observe the nano- and bio-fluidic flow phenomena. In this article, the basic principle of these high-tech flow visualization techniques and their practical applications which cannot be resolved by conventional methods, such as blood flows in a micro-tube, in vivo analysis of micro-circulation, and flow around a living body are introduced as a blue ocean strategy.

• Journal of the Korean Society of Visualization
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• v.10 no.3
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• pp.37-41
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• 2012

Plate-fin heat exchanger is a kind of compact heat exchangers with a good performance in heat transfer. It is widely used in various engineering fields such as aerospace, chemical and biomedical industries. Quantitative and qualitative flow visualization study were performed using the water model of commercial plate-fin heat exchanger with header angles of $30^{\circ}$. The Reynolds number was 100. Conventional digital particle image velocimetry was used to measure the instantaneous velocity fields of the header region and the flow visualization using dye injection and hydrogen bubble method were applied to capture the qualitative flow characteristics. The results showed the existence of separation flow region at the junction area and the bottom wall of the exit region.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.11-18
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• 1997

Scientific volume visualization addresses the representation, manipulation, and rendering of volumetric data sets, providing mechanisms for looking closely into structures and understanding their complexity and dynamics. In the past several years, a tremendous amount of research and development has been directed toward algorithms and data modeling methods for a scientific data visualization. But there has been very little work on developing a mathematical volume model that feeds this visualization. Especially, in flow visualization, the volume model has long been required as a guidance to display the very large amounts of data resulting from numerical simulations. In this paper, we focus on the mathematical representation of volumetric data sets and the method of extracting meaningful information from the derived volume model. For this purpose, a B-spline volume is extended to a high dimensional trivariate model which is called as a flow visualization model in this paper. Two three-dimensional examples are presented to demonstrate the capabilities of this model.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.50-53
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• 2005

The turbulent flow around a sphere was investigated in a streamwise meridian plane using two experimental techniques: smoke-wire flow visualization in wind tunnel at Re=5,300 and PIV measurements in a circulating water channel at Re=7,400. The smoke-wire visualization shows flow separation points near an azimuthal angle of $90^{\circ}$, recirculating flow, transition from laminar to turbulent shear layer, evolving vortex roll-up and fully turbulent eddies in the sphere wake. In addition, the mean flow pattern extracted by particle tracing method in water tunnel at Re= 14,500 reveals two distinct comparable toroidal(not closed) vortices in the recirculation region. The mean velocity field measured using a PIV technique demonstrates the detailed wake configuration of close symmetric recirculation and near-wake configuration with two toroidal vortices, reversed velocity zone and vorticity contours.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.3-7
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• 2004

In this paper, computational aeroacoustics (CAA) method is used for flow-noise analysis and flow-noise visualization. High order high resolution scheme of optimized high order compact is used to resolve the small acoustic quantities and large flow quantities at the same time. An adaptive nonlinear artificial dissipation model and generalized characteristic boundary condition are also used. Aeolion tone noise, cavity noise, and jet noise are investigated. The visualizations of flow-noise are successful and characteristics of noise are studied. It is observed that the propagation directivity of noise is different with that of flow. With the help of CAA method, the visualization of noise is possible.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.45-50
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• 2005

Characteristics of flows at T-junction duct with and without orifices are investigated in this paper. Experiments and PIV visualization were carried out for several flow rates. Two-dimensional PIV experimental apparatus was decided by numerical analysis. PIV visualization was also coded to visualize flow fields at junctions for two-dimensional case. For the PIV visualization system, Grey-Level Cross-Correlation particle tracking algorithm was used to calculate the flow fields. Vinyl chloride polymer particles of $100{\sim}150{\mu}m$ of diameter are used in this visualization. The PIV visualization results showed relatively good agreement with Experimental data.