Bed and wall shear stresses in smooth rectangular channels

Abstract

Various empirical equations for mean bed and wall shear stresses have been proposed for smooth rectangular open channels. Considering that the distribution of bed shear and wall shear stresses is affected by the cross-sectional shape, the gravity force based on the flow depth used to non-dimensionalize shear stresses in previous studies is modified to a parameter that includes the width and wetted-perimeter. This yields a new set of dimensionless equations for mean bed and wall shear stresses, and the wall/bed shear force ratio. These equations compared well with all available experimental data over a wide range of aspect ratios from 0.31 to 50. These equations also yield new relationships for bed and wall friction factors.

Keywords:

• Aspect ratio
• bed shear stress
• boundary shear stress distribution
• open channel
• wall shear stress

Data availability statement

All data used during the study appear in the submitted article. All laboratory data sets for the mean bed and wall shear stresses, with corresponding width/depth ratios, are summarized in the Appendix and compiled in Table A1.

Additional information

Funding

This study was partially funded by the National Key Research and Development Program of China [grant number 2018YFC1508402], National Natural Science Foundation of China [grant number 51679262, 52009144], and the IWHR Research & Development Support Program [HY0145B642017].