The influence of roughness geometry and Shields parameter on flow resistance in gravel-bed channels
✍ Scribed by Baiamonte, Giorgio; Ferro, Vito
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 477 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0360-1269
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✦ Synopsis
The spatial variability of bed particles of a gravel-bed channel is analysed and treated experimentally in order to simulate the effects of the arrangement of coarse bed elements on the flow resistance law. For the studied bed patterns, characterized by the concentration Γ of coarser elements arranged on the bed layer, a particle arrangement parameter α is proposed. The α parameter is useful for estimating the intercept b 0 of the semi-logarithmic flow resistance law deduced by flume measurements carried out for the hydraulic condition of large-scale and transition roughness. The differences between the experimental friction factor parameter values and the ones calculated by the proposed semi-logarithmic relationship are explained by the ratio between the Shields parameter and its critical value. The analysis shows that estimates of the friction factor parameter are not improved by introducing the Froude number into the flow resistance law.