Author(s): Dong Xu; Yuchuan Bai; Ante Munjiza; Eldad Avital; John Williams
Linked Author(s): John J.R. Williams
Keywords: Open channel bends; Turbulent flow; Large eddy simulation; Secondary current
Abstract: Flows in curved open channel bends widely exist in meandering rivers. The geometric curvature of the channel greatly complicates the flow behaviour insides due to the appearance of the secondary current, primary flow velocity redistribution and so on. The turbulent characteristics are also greatly affected by the primary and secondary flow structure alteration. Both the secondary flow structure and the flow turbulent characteristics greatly complicate the sediment transport and the bed topography evolution in natural alluvial channel bends. In this paper, we presented the investigation on the characteristics of turbulent flow in a meandering open channel bend based on numerical computations. Large eddy simulation (LES) was used for the computation, which adopted a finite-volume method based solver for incompressible viscous flow and a Smagorinsky-Lilly model for the subgrid viscosity calculation. Based on the simulation results, the turbulent structure in the channel bends was observed, as well as the secondary flow structure on cross-sections of the channel. The effect of width-to-depth ratio was also studied with LES, which was found presenting significant influence on the cross-sectional secondary currents and the transverse flow velocity, rather than the primary flow or the streamwise flow velocity.
Year: 2013