Author(s): Michio Sanjou; Iehisa Nezu

Linked Author(s):

Keywords: Coherent structure; Delta method; Meandering compound open-channel flow; PIV; Secondary currents; Turbulence

Abstract: Meandering compound open-channel flow is of high interest in river engineering and flood disaster. In particular, cross-sectional secondary currents develop significantly associated with an interaction between meandering inbank main-channel flow and straight overbank floodplain flow. These currents promote mass and momentum exchanges between them, as well as sediment transport and bed erosion. Further, organized motions may be generated in the same manner as typical horizontal vortices in straight compound channels. However, there is limited detailed information on the generation process of organized motion and secondary currents. This study focuses on the 3D structure of horizontal coherent motion and its advection property in the channel-transition zone from the straight to meandering compound open-channel flows by using a multi-layer scanning PIV, and compares them with those of continuous meandering channel flows.A strong relation between the horizontal vortices and secondary currents was obtained, resulting in a phenomenological flow model.

DOI: https://doi.org/10.3826/jhr.2009.3485

Year: 2009