二層PIVを用いた複断面開水路流れにおける乱流渦の三次元組織構造に関する実験的研究

抄録

In compound open-channel flows, there are some large-scale horizontal vortices with a vertical axis. Such coherent vortices influence significantly the transverse transport of scalar variables like suspended sediment between the main-channel and floodplains. So, it is very important in hydraulic engineering and river environment to investigate hydrodynamic characteristics of coherent horizontal vortices in compound open-channel flows and thus there are a lot of experimental and numerical studies on these topics. From recent measurements, it isinferred that the horizontal eddies have a 3-D structure of vortex tubes.
However, 3-D structure of horizontal vortices has not yet been revealed in detail. Therefore, in the present study, a new PIV system using dual-layer laser light sheets was developed and instantaneous velocity fields on two laser sheets were measured simultaneously. As a result, 3-D coherent properties of horizontal vortices and their convection mechanism have been investigated experimentally.