An inverted-churn flow is mentioned in the safety analysis of the boiler and the nuclear reactor. In the past experiment it remains a difficult job for observing the hydraulics characteristic of the inverted-churn flow. Not only for the experiment item measuring inverted-churn flow is limited, but also it is difficult for a visual observation to carry out as well. In our experiment, stereo images of inverted-churn flow that composed of air and water are taken using a stereo method. Moreover, a dynamic matching method and an optical flow method are adopted respectively to trace the liquid phase in the two-phase flow. Finally a Standard Deviation comparison between both methods and the normal visual observation is carried out respectively, and more accurate result is obtained.
