Development of 3D Micro-PIV techniques Applicable to Marangoni flows in small space

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The purpose of this research has been as follows ;1) Development of the measurement techniques that enable to measure instantaneous three-dimensional velocity distributions in micro-size flow fields.2) By utilizing the developed techniques, studying on interactions between surface tension and micro-flows.In this research, three kinds of imaging methods for the three-dimensional micro-PIV have been developed. The first method is a stereo-imaging method using a pair of telecentric lenses, that enables parallel projection stereo matching. The second method utilizes digital inline holography technique. The stereo inline holography technique developed in this research consists of a simple optical setup and an easy calibration method. It improves spatial resolution along the direction of optical axis. The third method is the defocus method using color eccentric apertures that can process higher distribution density of tracer particles than the ordinary defocus method.The ordinary stereo imaging setup is known to be weak in vibration and needs delicate optical alignment, especially when it is applied to tiny objects. In order to avoid the problems, some one-camera stereo imaging methods are developed. The one-camera stereo method is far robust against outside vibrations.The dimensions of measuring objects are assumed to be from some tens to hundred microns. Flows in such small space are strongly influenced by the surface tension. The major interest of the present research is an influence of surface tension and the Marangoni flows in micro-channels. Experiments concerning to the issues had not been executed, since it has taken long time to develop the measurement techniques. More experiments should be done to study the influence of surface tensions on the micro scale flows in near future.Adding to the optical methods, the feasibility study of the three-dimensional PIV technique using X-ray has done for the advanced PIV in the synchrotron radiation facility, SPRING-8.