Author(s): Xiaonan Tang
Linked Author(s): Xiaonan Tang
Keywords: Velocity distribution; Shear layer; Open channel; Analytical model
Abstract: Understanding of velocity distribution of flow in lateral shear layer of open channel is significant to many problems in river and eco-environment engineering, such as distribution of pollutant dispersion, sediment transport and bank erosion, and habitat etc. It is not well understood about how the velocity varies laterally in the wall boundary layer. In this paper, lateral velocity distribution has been developed based on the model proposed by Shiono & Knight (SKM), built on the depth-averaged momentum equation. The lateral velocity distributions in the lateral shear layer for rectangular open channels over a wide range of aspect ratios were obtained by the proposal model, so as to establish two hydraulic parameters of lateral eddy viscosity (λ) and depth-averaged secondary flow (Γ). The results show that the proposed velocity equation (15) models the experimental data well. Preliminary relationships between the above two parameters and the aspect ratio, B/H, are obtained, based on two sets of experimental data. The lateral extent of the shear layer was investigated and found to be related to the eddy viscosity parameter (λ) and the bed friction factor (f), as shown by equation (20). This indicates that the shear layer near the wall will be very wide (δ/H = 14. 6) for the worst case (λ =0. 6 and f=0. 01).
Year: 2013