• Title/Summary/Keyword: PIV

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Measurements of a microchannel flow using micro-PIV

  • Lee Inwon;Choi Jayho;Lee In-Seop
    • 한국가시화정보학회:학술대회논문집
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    • pp.44-52
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    • 2001
  • A micro-PIV(particle image velocimetry) measurement has been conducted to investigate flow fields in such microfluidic devices as microchannels and micronozzle. The present study employs a state-of-art micro-PIV system which consists of epi-fluorescence microscope, 620nm diameter fluorescent seed particles and an 8-bit megapixel CCD camera. Velocity vector fields with a resolution of $6.8\;\times\;6.8{\mu}m$ has been obtained, and the attention has been paid on the effect of varying measurement conditions of particle diameter and particle concentration on the resulting PIV results. In this study, the microfluidic elements were fabricated on plastic chips by means of MEMS processes and a subsequent molding process. Flow fields in a variety of microchannels as well as micronozzle have been investigated.

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PIV Analysis of Cubic Channel Cavity Flow (입방형 채널 캐비티 유동의 PIV 해석)

  • 조대환;김진구;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.5
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    • pp.557-563
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    • 1997
  • The unsteady flow in three-dimensional cubic cavity with narrow channel at upper region is investigated experimentally for three kinds of Reynolds number, 1*10/sup 4/, 3*10/sup 4/ and 5*10/sup 4/ based on the cavity width and cavity inlet mean flow velocity. Instant velocity vectors are obtained simultaneously at whole field by PIV(Particle Image Velocimetry). Wall pressure distributions are estimated using Poisson equation from the velocity data. Results of PIV reveal that severe unsteady flow fluctuation within the cavity are remarkable at all Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving flow is collided with the clock-wise rotating main primary vortex. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the entire region and spanwise kinetic energy migration is conspicuous.

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A PIV STUDY OF VORTEXING DURING DRAINING FROM Cylindric CONTAINERS (원형 용기의 중심에서 벗어난 유출구 위치에 따른 회전배수 특성의 PIV 연구)

  • Ju, M.G.;Sohn, C.H.;Gowda, B.H.L.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.89-92
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    • 2007
  • In the present study, the flow field in a square container with various comer rounding is studied to investigate drain flow characteristics. An attempt has been made to understand the mechanism that is responsible for vortex suppressing by the different radius of rounding at the comer. For this purpose, flow visualization studies using PIV (Particle Image Velocimetry) are employed to determine the flow patterns in a square tank. Results are obtained when there is no draining and with draining. The flow field is visualized both in horizontal and vertical planes.

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X-ray PIV Measurements of Velocity Field of Blood Flows

  • Lee, Sang-Joon;Kim, Guk-Bae
    • 순환기질환의공학회:학술대회논문집
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    • pp.28-36
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    • 2006
  • The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

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A Study on the Spray Characteristics of Small LRE Injector through PIV and PDA Measurements (PIV 및 PDA 계측에 의한 소형 액체로켓엔진 인젝터의 분무특성 연구)

  • Kim, Jin-Seok;Jung, Hun;Kim, Jeong-Soo;Park, Jeong;Kim, Sung-Cho;Choi, Jong-Wook;Jang, Ki-Won
    • 한국가시화정보학회:학술대회논문집
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    • pp.63-67
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    • 2006
  • Spray characteristics of an injector employed in mono-propellant hydrazine thrusters were investigated by PIV(particle image velocimetry) and PDA(phase Doppler anemometry) techniques. The instantaneous plane images captured by PIV measurement were examined in order to judge the pass-fail criteria of spray injection performance according to the specific pressure supplied. PDA technique was also applied to measure the velocity and droplet size of spray which were not obtainable by PIV measurement. The objective of this experimental study is the evaluation of the injector performance which may be utilized for the design of brand-new injector through the clear understanding of spray characteristics.

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A PIV STUDY OF VORTEXING DURING DRAINING FROM SQUARE CONTAINERS (정사각형 용기로부터 회전배수 특성의 PIV 연구)

  • Ju, M.G.;Sohn, C.H.;Gowda, B.H.L.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.313-316
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    • 2007
  • In the present study, the flow field in a square container with various corner rounding is studied to investigate drain flow characteristics. An attempt has been made to understand the mechanism that is responsible for vortex suppressing by the different radius of rounding at the corner. For this purpose, flow visualization studies using PIV (Particle Image Velocimetry) are employed to determine the flow patterns in a square tank. Results are obtained when there is no draining and with draining. The flow field is visualized both in horizontal and vertical planes.

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Quantitative Flow Field Visualization of a Flow inside an Opaque Tube Using Angiographic PIV Method (X선관을 이용한 불투명한 물체 내부 유동의 정량적 가시화 연구)

  • Kim, Guk-Bae;Lim, Nam-Yun;Ryu, Jae-Chun;Yim, Dae-Hyun;Lee, Hyung-Koo;Lee, Sang-Joon
    • Proceedings of the KSME Conference
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    • pp.2935-2940
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    • 2007
  • To diagnose circulatory diseases in the viewpoint of hemodynamics, we need to get quantitative hemodynamic information of blood flows related with the vascular diseases with high spatial resolution of tens micrometer and high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena, a new diagnosing technique combining medical radiography and PIV method was newly proposed and developed. This angiographic PIV technique consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulses of X-ray, and a synchronizer. The feasibility of the angiographic PIV technique was tested and quantitative flow velocity field distribution of a flow inside an opaque conduit was acquired by the developed system. It can be used for measuring flow phenomena of nontransparent fluids inside opaque conduits.

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A Diagnostic Technique for the Air Flow Characteristics in Refrigerators using PIV (PIV에 의한 냉장고 기류특성 평가방법)

  • Kim, Seok-Ro;Doh, Deog-Hee;Lee, Jae-Keun;Kim, Kyung-Chun
    • Proceedings of the SAREK Conference
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    • pp.576-584
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    • 2007
  • A PIV(Particle Imaging Velocimetry) diagnostic technique for the evaluation of the flow characteristics in refrigerator is introduced. Smoke particles of which density is small enough to follow up the air flow are used for visualization of the air flows in the refrigerators. A rectangular room model is tested for the verifications of the dignostic technique. By evaluating the turbulent intensity and the deviation value of the turbulent intensity distribution that were obtained from PIV results, an optimal ventilating condition is suggested. The constructed technique is used for the diagnostics on the flow of an actual refrigerator. It has experimentally proved that the present technique is able to evaluate the ventilation conditions of refrigerators.

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A Research on the Vector Search Algorithm for the PIV Flow Analysis of image data with large dynamic range (입자의 이동거리가 큰 영상데이터의 PIV 유동 해석을 위한 속도벡터 추적 알고리즘의 연구)

  • Kim Sung Kyun
    • 한국전산유체공학회:학술대회논문집
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    • pp.13-18
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    • 1998
  • The practical use of the particle image velocimetry(PIV), a whole-field velocity measurement method, requires the use of fast, reliable, computer-based methods for tracking velocity vectors. The full search block matching, the most widely studied and applied technique both in area of PIV and Image Coding and Compression, is computationally costly. Many less expensive alternatives have been proposed mostly in the area of Image Coding and Compression. Among others, TSS, NTSS, HPM are introduced for the past PIV analysis, and found to be successful. But, these algorithms are based on small dynamic range, 7 pixels/frame in maximum displacement. To analyze the images with large displacement, Even and Odd field image separation and a simple version of multi-resolution hierarchical procedures are introduced in this paper. Comparison with other algorithms are summarized. A Results of application to the turbulent backward step flow shows the improvement of new algorithm.

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Analysis on Cold Air Circulation of a Domestic Refrigerator Freezer by PIV Animation (PIV 애니메이션에 의한 가정용 냉장고 냉동실의 냉기 순환 해석)

  • Kim, J.Y.;Yang, C.J.;Kim, J.H.;Lee, Y.H.
    • Proceedings of the KSME Conference
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    • pp.686-691
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    • 2000
  • Animation technique from the PIV database is particularly emphasized to give macroscopic and Quantitative description of complex flow fields. As an example, an experimental study was carried out investigate the fundamental (low characteristics of the freezer with the domestic refrigerator. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. Image intensifier CCD camera to cope with illumination problem is arranged for the accurate PIV measurement of large flow field. As a results, continuous pictures of the spatial distribution of the instantaneous and time-mean velocity distribution are displayed in real-time sense.

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