Numerical Study on the Effects of the Floodplain Width on Flow Field and Interaction between the Main Channel and Floodplains in Prismatic Compound Channels

Prediction of flow field in compound channel is an important task for hydraulic researches because of the three dimensional nature of the flow. In compound channels with prismatic floodplains, the main feature consists of the interaction effect between the fast moving flow in the main channel and the slow moving flow on the floodplains. This difference creates a high shear layer at the interface between the main channel and floodplains, leading to the generation of the large scale vortices with vertical axes, as well as the helical secondary with longitudinal axes, as shown by Sellin [1], Tominaga and Nezu [2], Ikeda [3], Bousmar [4] and Rezaei [5].