• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.391-397
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• 2004

This paper presented results of experimental and numerical work for natural convection in a square enclosure by using PIV technique. 2D PIV technique and liquid crystal are employed for velocity and temperature measurement in water. The numerical method used this work is a CFD corde, STAR-CD. The experimental work are compared with these of numerical results.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.175-178
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• 2001

In a clothes dryer, various thermo-fluid flow phenomena occur such as the heat and mass transfer in the process of removing moisture from clothes, the flow field generated by the fan, and the various flow characteristics from the complex flow paths. The study and understanding of such phenomena is an important factor in increasing the performance of dryers. In this study, as part of a dryer research, the flow field inside a vented dryer was measured using PIV, which the result will be used as the basic material in analyzing the various flow phenomena.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.93-98
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• 2005

The mean and RMS velocity field of the respiratory gas flow in tile human airway was studied experimentally by particle image velocimetry(PIV). Some researchers investigated the airflow for the mouth breathing case both experimentally and numerically. But it is very rare to investigate the airflow of nose breathing in a whole airway due to its geometric complexity. We established the procedure to create a transparent rectangular box containing a model of the human airway for PIV measurement by combination of the RP and the curing of clear silicone. We extend this to make a whole airway including nasal cavities, larynx, trachea, and 2 generations of bronchi. The CBC algorithm with window offset (64*64 to 32*32) is used for vector searching in PIV analysis. The phase averaged mean and RMS velocity distributions in Sagittal and coronal planes are obtained for 7 phases in a respiratory period. Some physiologic conjectures are obtained. The main stream went through the backside of larynx and trachea in inspiration and the frontal side in expiration. There exist vortical motions in inspiration, but no prominent one in expiration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.71-76
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• 2017

The roll damping problem in the design of ships and offshore structures remains a challenge to many researchers due to the fluid viscosity and nonlinearity of the phenomenon itself. In this paper, the study on viscous roll damping of a circular cylinder was carried out using forced oscillations. The roll moment generated by forced oscillation using a torque sensor was measured for each forced oscillation period and compared with the empirical formula. Although the magnitude of the measured torque from the shear force was relatively small, the results were qualitatively similar to those obtained from the empirical formula, and showed good agreement with the quantitative results in some oscillation periods. In addition, the flow around the circular cylinder wall was observed closely through the PIV measurements. Owing to the fluid viscosity, a boundary layer was formed near the wall of the circular cylinder, and a minute wave was generated by periodical forced oscillations at the free surface through the PIV measurement. In this study, the suitability of the empirical formula for the roll moment caused by viscous roll damping was verified by model tests. The wave making phenomenon due to the fluid viscosity around the wall of a circular cylinder was testified by PIV measurements.

• Journal of the Korean Society of Visualization
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• v.10 no.3
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• pp.30-36
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• 2012

We are planning to construct a scaled-down moderator facility to simulate the CANDU-6 moderator circulation phenomena during steady state operating and accident conditions. In the present work a preliminary experiment using a 1/40 scaled-down moderator tank has been performed to investigate the anticipated problems of the flow visualization and measurement in the planning scaled-down moderator facility. We shortly describe CFD analysis result for the 1/40 scaled-down test model and the flow measurement techniques used for this test facility under isothermal flow conditions. The Particle Image Velocimetry (PIV) method is used to visualize and measure the velocity field of water in a transparent Plexiglas tank. Planar Laser Induced Fluorescence (PLIF) technique is used to evaluate the feasibility of temperature field measurement in the range of $20-40^{\circ}C$ of water temperature using an one-color method.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.2
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• pp.30-35
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• 2003

Flow characteristics of blood flow in a micro channel were investigated experimentally using a micro-PIV (Particle Image Velocimetry) velocity field measurement technique. The main objective of this study was to understand the real blood flow in micron-sized blood vessels. The Reynolds number based on the hydraulic diameter of micro-channel for deionized (DI) water was about Re=0.34. For each experimental condition, 100 instantaneous velocity fields were captured and ensemble-averaged to get the spatial distributions of mean velocity. In addition, the motion of RBC (Red Blood Cell) was visualized with a high-speed CCD camera. The captured flow images of nano-scale fluorescent tracer particles in DI water were clear and gave good velocity tracking-ability. However, there were substantial velocity variations in the central region of real blood flow in a micro-channel due to the presence of red blood cells.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.702-707
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• 2001

The characteristics of flow in dividing regions are precise, therefore their classification is very important not only in industry but also in hydrodynamics. By now, many studies of flow in dividing regions have been performed, but flow characteristics that use visualization in dividing regions have not been studied. The present study of the PIV and the CFD exhibit average velocity distributions, kinetic energy distributions and total pressure distributions etc of the total flow field due to the development of the accurate visualization optical laser and of optical equipment. Also, PIV is accurate with the flows characteristics of the dividing region as continuous analysis is done using input equipment. The study analyzes average velocity vector field, average kinetic energy, x-axis stress distributions, average and total pressure distributions of dividing regions with flow for visualization of the PIV and the CFD measurement in a dividing rectangular duct.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.188-196
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• 1997

Many researchers have developed the measurement technique of in-cylinder flow characteristics and found the effect of intake port geometries on engine performance. The flow characteristics of four-valve cylinder head were examined in a steady flow rig for different intake ports. Tumble intensity of intake configurations with different entry angles were quantified with a tumble meter. The velocity and angular momentum distributions in the tumble adaptor were measured under steady conditions with PIV(Particle Image Velocimetry). We have obtained the results that flow structure becomes complicated by valve interference at low valve lift. As the valve interferences were reducing and the flow pattern changed to large vortex structure with tumble direction, intake ports with different entry angles have different tumble centers. Tumble eccentricity of intake port with low entry angle was large, so that the port had relatively much angular momentum compared to others which was expected to improve combustion performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.595-601
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• 2001

We applied PIV method to obtain instantaneous and ensemble averaged velocity fields from the first row to the fifth row of a staggered tube bundle. The Reynolds number based on the tube diameter and the maximum velocity was set to be 4,000. Remarkably different natures are observed in the developing bundle flow. Such differences are depicted in the mean recirculating bubble length and the vorticity distributions. The jet-like flow seems to be a dominant feature after the second row and usually skew. However, the ensemble averaged fields show symmetric profiles and the flow characteristics between the third and fourth measuring planes are not so different. comparison between the PIV data and the RANS simulation yields severe disagreement in spite of the same Reynolds number. It can be explained that the distinct jet-like unsteady motions are not to be accounted in th steady numerical analysis.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.886-892
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• 2008

The development of fluid mechanics is briefly reviewed and the importance of fluid flows to heat and mass transfer in nature as well as to science and engineering is outlined. This paper presents the experimental results of air flow in the rectangular tunnel which has four different exhaust outlets, each distance of which from the inlet is 0, 30, 60 and 90mm respectively. This experiment is conducted by using the olive oil as the tracer particles and the kinematic viscosity of the air flow is $1.51{\times}10^{-5}\;m^2$/s. The flow is tested at the flow rate of 1.3 $m^3$/h and the velocity of 0.3 m/s. PIV technology can be used to make a good description of the smoke flow characteristics in the tunnel.