抄録
Lithting with stroboscopes are used for the hydrogen bubble technique to determine the instantaneous velocity field of the two-layered flow. The stroboscopes light simultanously, at constant frequency, 2 or 3 times while the camera shutter is opened. Such, 2 or 3 images of the same moving time lines of hydrogen bubbles are taken on each photograph. During the measurement of the velocities the interfacial waves of the flow are visualized with fluorescin dye. This method is recognized to be useful to detemine the relation between the spatial distribution of the velocities and their turbulent fluctuations and the interfacial waves of the two-layered flow.
