抄録
This paper presents a new micro-flow diagnostic technique, "confocal micro- particle image velocimetry (PIV)", and its application to the internal flow measurement of a droplet passing through a square microchannel. The confocal micro-PIV system enables us to obtain a sequence of sharp and high-contrast cross-sectional particle images at 2,000 frames per second. Using the present confocal micro-PIV system, we can measure velocity distributions of micro-flows in a 240 × 180 gm region with a confocal depth of 1.88 gm. We also propose a three-dimensional velocity measurement method based on the confocal micro-PIV and the equation of continuity. This method enables us to measure three velocity components in a three-dimensional domain of micro flows. The confocal micro-PIV system is applied to the internal flow measurement of a droplet. We have measured cross-sectional velocity fields at different focal positions of a droplet traveling in a 100 gm (width) × 58 gm (depth) channel. A volumetric velocity distribution inside a droplet is obtained by the confocal micro-PIV and the three-dimensional flow structure inside the droplet is investigated. The measurement results suggest that a three-dimensional and complex circulating flow is formed inside the droplet.
