Author(s): C. Zeng; C. W. Li
Keywords: Hybrid RANS-LES model; Open-channel flow; T-diversion; Turbulence modeling
Abstract: The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage purposes. To accurately predict the mean flow and turbulence characteristics of this flow phenomenon, a hybrid RANS-LES (Reynolds Averaged Navier-Stokes equation–Large Eddy Simulation) model is proposed in the present study. In the upstream and downstream regions of the main channel, as well as the downstream region of the branch channel the unsteady RANS model is used. In the channel diversion region in which the turbulence flow characteristics are complicated the LES model is used. Isotropic velocity fluctuations are added at the inflow interface of the LES region to trigger the generation of resolved turbulence. The hybrid approach saves computational effort and does not have difficulties in the proper specification of inlet and outlet boundary conditions. The comparison between the computational results and the experimental data indicates that this relatively new modeling approach can predict the openchannel T-diversion flows accurately.