トレーサを利用した実河川水制周辺流れのビデオ画像解析

抄録

Surface flow patterns between groins located in a middle reach of the Nagara river are visualized and measured by an image analysis method. Shock absorbing particles made of corn starch are used as tracer to visualize the surface flow as they are easily dissolved into water and harmless to the environment. Visualized flow patterns are shot by a digital video camera from an oblique angle, transferred to a personal computer as a movie file, which is divided into a series of bit map files, transformed into non-distorted images, and analyzed by PIV (Particle Imaging Velocimetry) to obtain instantaneous and average two-dimensional surface velocity distributions. In addition, streak patterns of recirculating flows between the groins are made clear by superposing hundreds of images. The results demonstrated that the respective inter-groin velocity pattern shows completely different flow features depending on their relative locations.