A flow pattern with varying aspect ratio (breadth/depth) and boundary roughness ratio (bed roughness/ side wall roughness) in open channel is proposed in this paper. The distribution of boundary shear and the mean boundary shear are studied. On the basis of this, velocity distribution and flow resistance are further discussed. The evaluation formulae of boundary shear, velocity distribution and flow resistance are derived systematically. The results are suitable for all aspect ratio and roughness ratio, and are better in agreement with a wide range of experimental data. These are much helpful to the study of sediment transport, flow diffusion, river engineering, etc.
The friction factor of flow on a flat bed consisting of sands decreases when the sands on the bed are transported by the flow. In this paper, the equations of velocity distribution and friction factor on a flat movable bed are derived on the basis of a two layer flow model with water flow layer and sand-water flow layer. Theoretical values of velocity distribution are compared with the experimental ones and show good agreement with them. As the results, the differences in the velocity and the friction factor between the fixed and movable beds are crarified.
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