LARGE EDDY SIMULATION OF OPEN CHANNEL FLOWS WITH NONSUBMERGED VEGETATION

Results of several Large Eddy Simulations (LES) of open channel flows with non-submerged vegetation are presented in this article. It is shown that the vegetation can make the flow structure in the mainstream direction uniform for both supercritical and subcritical flows. For subcritical flows, the LES results of the ensemble-average of time-averaged velocity distributions at four vertical sections around a single plant are in good agreement with measurements. The velocity sees double peaks at the upper and lower positions of flows. For supercritical flows, the ensemble-average velocities see some discrepancy between LES and measurement results. Some secondary flow eddies appear near the single plant, and they just locate in the positions of the double peaks in stream-wise velocity profiles. It is also found that the vegetation drag coefficient deceases as the Froude number increases.