Abstract
Shear stress comprises basic information for predicting the average depth velocity and discharge in channels. With knowledge of the percentage of shear force carried by walls (%SFw) it is possible to more accurately estimate shear stress values. The %SFw, non-dimension wall shear stress () and non-dimension bed shear stress () in smooth rectangular channels were predicted by a three methods, the Bayesian Regularized Neural Network (BRNN), the Radial Basis Function (RBF), and the Modified Structure-Radial Basis Function (MS-RBF). For this aim, eight data series of research experimental results in smooth rectangular channels were used. The results of the new method of MS-RBF were compared with those of a simple RBF and BRNN methods and the best model was selected for modeling each predicted parameters. The MS-RBF model with RMSE of 3.073, 0.0366 and 0.0354 for %SFw, and respectively, demonstrated better performance than those of the RBF and BRNN models. The results of MS-RBF model were compared with three other proposed equations by researchers for trapezoidal channels and rectangular ducts. The results showed that the MS-RBF model performance in estimating %SFw, and is superior than those of presented equations by researchers.
Highlights
The determination of shear stress distribution is key in identifying the hydraulic induced sediment transport phenomena
Bed shear stress dominantly is responsible for the calculation of bedload transport and wall shear stress becomes effective in the discussion of channel migration and bank erosion
Eight series of experimental data are used to predict the percentage of shear force carried by walls in smooth rectangular channels
Summary
The determination of shear stress distribution is key in identifying the hydraulic induced sediment transport phenomena. Shear stress parameter ascribes to the fluid-sediment interaction in the threshold of erosion and depositions, sediment incipient motion, and transport rates [1,2]. The boundary layer or near bed shear stress determines the mode of sediment transport either suspension or as bed load movement. Forecasting shear stress parameters in rectangular channels using new soft computing methods weight of flowing water flowing onto the boundary [3]. Bed shear stress dominantly is responsible for the calculation of bedload transport and wall shear stress becomes effective in the discussion of channel migration and bank erosion
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