Reproduction of turbulence characteristics in a channel bend using LES

Abstract

In order to develop a Large-eddy Simulation (LES) method that will be applicable to real river flows, a numerical method based on the moving curvilinear coordinates has been developed and applied to a flow in a channel bend. The flow in a channel bend is a good benchmark test case for numerical simulation method since it has many important elements essential to real river flows. There are experimental data and calculation using more conventional Reynolds-averaged Navier-Stokes (RANS) methods. By directly simulating the large-scale flows with about 50 percent of the fluctuating velocities resolved, the present method is found to reproduce the mean streamwise velocity and the secondary flow very well and the turbulent stresses and the free-surface fluctuation are reproduced reasonably well.