複断面開水路流れにおける大規模水平渦の発生と発達

抄録

Two-dimensional numerical calculation and theoretical stability analysis for open channel flow was executed to make clear the characteristics of large surface-eddies which appears in compound open channels. Characteristics of large surface-eddies in compound open channel were claccified into generation and evolution processes. In the generating process, linear stability analysis in 2-dimensional shear layer flow with finite width of channel shows that wave length in the generating process becomes longer as width of channel becomes narrower. Characteristic of surface-eddies in evolution process is as follows. 1) Patterns of large surface-eddies has two patterns, periodical and chaotic. 2) Time-period of large surface-eddies decreases as velocity difference between main channel and floodplain increases. 3) Wave number increases with Reynolds number defined by eddy viscosity, and chaotic pattern of large surface-eddies exist in the range of high Reynolds number.