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Research Papers: Micro/Nanoscale Heat Transfer

# Measurements of Three-Dimensional Flow in Microchannel With Complex Shape by Micro-Digital-Holographic Particle-Tracking Velocimetry

[+] Author and Article Information
Shin-ichi Satake, Takafumi Anraku, Hiroyuki Kanamori

Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Tomoaki Kunugi

Department of Nuclear Engineering, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo, Kyoto 606-8501, Japan

Kazuho Sato

Toyota Industries Corporation, 2-1 Toyoda cyou, Kariya, Aichi 448-8671, Japan

Tomoyoshi Ito

Japan Science and Technology Agency (JST), Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan and Department of Electronics and Mechanical Engineering, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan

J. Heat Transfer 130(4), 042413 (Mar 21, 2008) (7 pages) doi:10.1115/1.2818783 History: Received June 21, 2007; Revised July 06, 2007; Published March 21, 2008

## Abstract

High time-resolution flow field measurement in two microchannels with a complex shape is performed by a micro-digital-holographic particle-tracking velocimetry (micro-DHPTV). The first microchannel has a $Y$ junction that combines the flow of fluid from two inlets into one outlet. In this case, two laminar velocity profiles from the inlet regions merge into one laminar velocity profile. The second microchannel has a convergence region from where a fluid flows into a divergence region. At this region, two recirculation regions appear. Consequently, approximately 250 velocity vectors in both cases can be obtained instantaneously. For a microchannel with the convergence region, the two recirculation regions that appear at the divergence point are captured from a three-dimensional vector field, with which the axes of recircular vortices have some alignment. The reason why we can observe this phenomenon is that a three-dimensional velocity, including the depth direction, can be obtained by micro-DHPTV.

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## Figures

Figure 1

Optical setup

Figure 2

Schematic of the Y-junction microchip: (a) microchip, (b) Y junction, and (c) cross section of the microchannel

Figure 3

Schematic of the microchip with a convergence region: (a) microchip, (b) a convergence region, (c) cross section of the microchannel

Figure 4

Fringe image of the microchannel with a Y junction: (a) Real image. (b) This image is the deducted background image from the real image.

Figure 5

Fringe image of the microchannel with a convergence region: (a) Real image. (b) This image is the deducted background image from the real image.

Figure 6

Reconstruction of particles in the microchannel with the Y junction

Figure 7

3D velocity vectors in the microchannel with the Y junction

Figure 8

Reconstruction of particles in the microchannel with a convergence region

Figure 9

3D velocity vectors in the microchannel with a convergence region

Figure 10

Schematic viewgraph of the microchannel with a convergence region: Line A is defined by Z=28.2μm located from the upper wall of the microchannel. Line B is defined by Z=39.3μm located from the upper wall of the microchannel. Line C is defined by Z=50.4μm located from the upper wall of the microchannel.

Figure 11

Time averaged velocity profile in 2s calculated at lines A, B, and C: (a) two-dimensional velocity vectors on line A in Fig. 1 at the x-y plane, (b) two-dimensional velocity vectors on line B in Fig. 1 at the x-y plane, and (c) two-dimensional velocity vectors on line C in Fig. 1 at the x-y plane

Figure 12

Schematic viewgraph of the microchannel with a convergence region: Line A is defined by Y=133.4μm located from the upper side of the observation area. Line B is defined by Y=203.8μm located from the upper side of the observation area. Line C is defined by Y=304.2μm located from the upper side of the observation area.

Figure 13

Time averaged velocity profile in two 2s calculated at lines A, B, and C: (a) two-dimensional velocity vectors on line A in Fig. 1 at the y-z plane, (b) two-dimensional velocity vectors on line B in Fig. 1 at the y-z plane, (c) two-dimensional velocity vectors on line C in Fig. 1 at the y-z plane

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