| Summary: | 碩士 === 國立清華大學 === 工程與系統科學系 === 97 === In this paper, three-dimensional movements of the particles inside the Stagger Herringbone Micro-mixer (SHM) were visualized by a wide-range defocusing particle tracking velocimetry (WDPTV). WDPTV is a simple method to obtain three dimensional information inside the micro-channels through a single camera setup. The principle of this method is based on the changes of the diffraction pattern at different defocusing distance. The radius changes of the defocusing particle images at different defocusing distances were recorded, and by correlating the images with the defocusing distances, the three dimensional location of the particles inside micro-fluidic device can be estimated. By adjusting the cover glass offset value on the objective, the spherical aberration effect will be inverted, thus ,the measurement range at the same defocusing distance could be increased to 200μm. This technique had been successfully applied to different micro-mixers including SHM, and the three dimensional flow fields were reconstructed to further study the mixing mechanism. This system can extract three dimensional information through simple setup and provide in situ information about the geometric effects of the micro mixers.
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