Three-Dimensional Hydrodynamics of Meandering Compound Channels

Abstract

The velocity field in meandering compound channels with overbank flow is highly three dimensional. To date, its features have been investigated experimentally and little research has been undertaken to investigate the feasibility of reproducing these velocity fields using computer models. If computer modeling were to prove successful in this context, it could become a useful prediction technique and research tool to enhance our understanding of natural river dynamics. In particular, an accurate computer prediction of the velocity field could benefit studies of channel morphology and pollution transport. In this paper, a meandering channel experiment from the U.K. Flood Channel Facility is simulated using computational fluid dynamics and the predicted velocities compared with the experimental data. Particular attention is paid to the reproduction of the secondary velocities and the helical motion of the water flowing within the main channel. Sensitivity tests of mesh design, discretization scheme, and roughness height are reported, together with the turbulence characteristics of the flow.