Reynolds Stress Modelling of Flow in Compound Channels with Vegetated Floodplains

Flow in compound channel with vegetated floodplain is complex and efficient modelling should include the effects of vegetation on velocity, secondary flow and shear stress. In the present study, the Volume-averaged Reynolds-averaged Navier-Stokes equations, in conjunction with a Reynolds Stress turbulence model, are solved numerically for a non-symmetrical compound channel of a trapezoidal main channel and a vegetated floodplain. The numerical results agree well with available experimental data, while the model is capable to reproduce the evolution of vortices. The cross-sectional flow characteristics reveal the momentum exchange mechanism between main channel and floodplain due to increased shear stresses and turbulence anisotropy near the vegetation interface. Also, the recently improved analytical Shiono and Knight method 1991. Turbulent open-channel flows with variable depth across the channel. J Fluid Mech. 222:617-646J is applied for the determination of the depth-averaged velocity and shear stress, together with simple Manning calculations.