NUMERICAL SIMULATION OF FLOW AROUND A BEND WITH GRAVEL BAR

Abstract

The flow around a bend of a real river reach during floods has been simulated by a Large-Eddy Simulation (LES) method in order to investigate the detailed flow characteristics and their effects on the gravel bars that exist on the inner banks of the meandering river reach. The hydrodynamic effects of flood flows near the gravel bar are thought to be closely related to the conditions for plant communities of diverse species to be maintained. The present numerical simulation, that represents the bed bathymetry to about 15 centimeters in the vertical direction, is found to reproduce the observed water level and slopes of a few hundred meter long reach for given discharges of a few hundred tons/sec. The simulated results include the three-dimensional velocity distributions and the bed shear stress along with the instantaneous secondary flow features and provide important information to study the hydrodynamic effects of flood flows on the gravel-bar plants.