Abstract
Large Eddy Simulation using the Smagorinsky model of turbulent flow is carried out for a straight open channel with one flood plain. The Reynolds number based on hydraulic radius and cross-sectional average velocity is about 5, 300, and the total number of grid points is 79*75*220. The calculated results agree reasonably well with the experimental data by Tominaga & Nezu in mean velocities and turbulence quantities. Then, the balances of the streamwise vorticity equation and the momentum equations are analyzed to discuss the mechanism of mean secondary flow. Instantaneous flow field is also visualized. It is confirmed that the present simulation captures streak structures and that instantaneous secondary flow near the edge of flood plain has unsteady and localized features with large magnitude in velocity.
