Author(s): Thorsten Stoesser; Wolfgang Rodi; Ceyda Polatel; Virendra C. Patel; Marian Muste
Keywords: Large Eddy Simulation; Turbulence; Dunes; Open-channel flow; Coherent structures
Abstract: This paper presents Large Eddy Simulation (LES) of turbulent open channel flow over a two-dimensional dune. The results of the computations are compared with recently reported Laser Doppler Velocimetry (LDV) measurements. The experimental data validate the simulations, which in turn provide an ideal complement to the experiments in order to investigate the mean and instantaneous flow properties with a high spatial resolution. The Reynolds number Reτ, based on the average friction velocity uτ and the average flow depth h, is approximately 3000. The time-averaged velocities calculated by the LES are in very good agreement with the observed data predicting all the features of the turbulent flow over dunes. In addition, the second order statistics, namely the Reynolds stresses show a good match to the LDV measurements. Furthermore, the instantaneous flow field is investigated with special emphasis on the occurrence of coherent structures.