Author(s): Sean Jiang; C. J. Tang; Yee-Chung Jin
Linked Author(s): Yee-chung Jin
Keywords: Bed shear; Open channel; Model
Abstract: An empirical model is developed for predicting the distribution of boundary shear stress around the wetted perimeter of an open channel. The longitudinal vorticity equation is simplified to include only the secondary Reynolds stress term. The driving force of the vorticity is modelled using a universal function. The effect of Reynolds shear stress is related to the second power of the vertical gradient of secondary velocity. The prediction model on the channel beds is derived based on a simplified longitudinal vorticity equation. The prediction model on the sidewalls is obtained by applying the model derived from the bed to the channel sidewalls due to the similarity of the secondary cell structures along the corner bisectors. In a case of trapezoidal open-channels, when the internal angle between the bed and sidewall equals 900 (i. e., rectangular open-channels), the boundary shear stresses can be obtained accordingly using the prediction model. The predicted results in both trapezoidal and rectangular open channels are validated with the published experimental data. It is concluded that the empirical model can be used for the prediction of the lateral distribution of boundary shear stress in open channels.