• Title/Summary/Keyword: 입자영상유속계

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A Quantitative Visualization of Mixed Convection in Parallel Plates Using PIV (PIV를 이용한 평행평판 내의 혼합대류의 정량적 가시화)

  • 박일용;배대석
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.3
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    • pp.509-515
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    • 2004
  • The PIV(Particle Image Velocimetry) with liquid crystal tracers is used for visualizing and analysis of the mixed convection in the parallel plates with the upper part cooled and the lower part heated. It is found that the flow pattern of mixed convection in the parallel plates can be classified into three patterns which was affected by Reynolds number. Also, the periodic nature is confirmed, and visualized in experiment.

An Experimental Study on the Wake with Swirling Flow in a Horizontal Circular Tube (수평원통관에서 선회유동의 후류에 관한 실험적 연구)

  • Kang Chang-Soo;Chang Tae-Hyun
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.5-9
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    • 2004
  • An experimental study is performed turbulent swirling flow behind a crcular cylinder using 2-D PIV technique. The Reynolds number investigated is 15,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the cylinder along the test tube.

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An Experimental Study on the Wake of a Square Cylinder Using PIV Technique (PIV기법을 이용한 정사각 실린더의 후류에 관한 실험적 연구)

  • 이종붕;장태현
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.1
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    • pp.124-135
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    • 2004
  • An experimental study is performed turbulent flow behind a square cylinder by using 2-D PIV technique. The Reynolds number investigated are 10.000. 30.000 and 50,000. The mean velocity vector, time mean axial velocity turbulence intensity. kinetic energy and Reynolds shear stress behind the cylinder are measured, The numerical method used this study is a CFD code, STAR-CD. The numerical results are compared with these of experimental.

A Study on Wake Flow Characteristics of vertical Plate with Various Coner Shape (모서리 형상에 따른 수직벽 후류특성에 관한 연구)

  • Lee, Cheol-Jae;Cho, Dae-Hwan
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.101-106
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    • 2011
  • In this study, the velocity distribution according to upper side coner shape of underwater construction with rectangular cylinder was measured with PIV method and the wake flow characteristics was considered. According to the coner shape, the flow pattern of wake flow was also differed greatly and the step-shaped coner of cut-off ratio B/H=0.06 was similar in the slope shape in result.

An Experimental Study on Selective Withdrawal from Linear Stratified Tank (선형 성층수조에서의 선택취수에 관한 실험적 연구)

  • Kim, Young Do;Park, Jae Hyeon;Son, Byung Ju
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.6B
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    • pp.499-505
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    • 2011
  • The mixing behavior of turbidity currents in a reservoir is closely related with the annual temperature change of the reservoir. In the summer, the reservoir has a well defined structure: one or two thermoclines and some layers of different densities. This density stratification inhibits vertical mixing and affects various hydrodynamic processes within the reservoir. Therefore, many reservoirs can be operated to release water of the specific quality with the selective withdrawal. In this study, the hydraulic experiments were performed to analyze the efficiency of selective withdrawal. The velocity distributions are measured with PIV in the stratified tank with the "two-tank" method. The relationship between the Richardson number and the selective withdrawal efficiency are provided using the measured velocity distributions.

Development of Fast and Exact FFT Algorithm for Cross-Correlation PIV (상호상관 PIV기법을 위한 빠르고 정확한 FFT 알고리듬의 개발)

  • Yu, Kwon-Kyu;Kim, Dong-Su;Yoon, Byung-Man
    • Journal of Korea Water Resources Association
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    • v.38 no.10 s.159
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    • pp.851-859
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    • 2005
  • Normalized cross-correlation (correlation coefficient) is a useful measure for pattern matching in PIV (Particle Image Velocimetry) analysis. Because it does not have a corresponding simple expression in frequency domain, several fast but inexact measures have been used. Among them, three measures of correlation for PIV analysis and the normalized cross-correlation were evaluated with a sample calculation. The test revealed that all other proposed correlation measures sometimes show inaccurate results, except the normalized cross-correlation. However, correlation coefficient method has a weakpoint that it requires so long time for calculation. To overcome this shortcoming, a fast and exact method for calculating normalized cross-correlation is suggested. It adopts Fast Fourier Transform (FFT) for calculation of covariance and the successive-summing method for the denominator of correlation coefficient. The new algorithm showed that it is really fast and exact in calculating correlation coefficient.

The Effect of Bottom Gap Size of Submerged Obstacle on Downstream Flow Field (수중 장애물의 하부틈새 크기가 하류 유동장에 미치는 영향)

  • Cho, Dae-Hwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.14 no.4
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    • pp.333-338
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    • 2008
  • The coastal zone is a delicate and dynamic area in which the majority of a water kinetic energy is dissipated. These processes are subsequent to the transport of the beach materials. In comparison to emerged breakwaters, submerged structures permit the passage of some wave energy and in turn allow for circulation along the shoreline zone. This research aims to examine the beach erosion prevention capability of submerged structure by laboratory model. The flow characteristics behind a submerged obstacle with bottom gap were experimentally investigated at Re = $1.2{\times}10^4$ using the two-frame PIV(CACTUS 2000) system. Streamline curvature field behind the obstacle has been obtained by using the data of time-averaged mean velocity information. And the large eddy structure in the separated shear layer seems to have signification influence on the development of the separated shear layer. As bottom gap size increases, the recirculation occurring behind the obstacle moves toward downstream and its strength is weakened.

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