わんど形状が河川に及ぼす影響に関する水理学的研究

抄録

There are several embayments so-callde “Wando”, which are located at riverbank andhave dead zones, in Japanese natural rivers. The characteristics of water fluctuations and their frequency have been investigated to some extent. In contrast, turbulence measurements in an around embayments have not been conducted as yet. However, it is quite important to investigate the turbulent characteristics in and around embayments, because mass and momentum exchanges between the main channel and embayment are generated by the turbulence.
In this study, the turbulence measurements in and around embayments were conductedby making use of a two-component laser Doppler anemometer (LDA) and ultrasonic water-wave gages. The aspect ratio of the downstream length L and spanwise length of embayment B_w were changed widely. Further, the behavior of the coherent vorticies was measured by Particle-image Velocimetry (PIV). Several new findings, such as the mass and momentum exchange rates were investigated experimentally.