The ratio of the mean shear stresses generated on the bed versus the banks of an open channel driven by flowing water is________________?
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Answer: C. greater than 1
Explanation
Mean shear stress on the bed of an open channel is typically greater than that on the side banks. Side wall friction reduces the effective shear stress acting on the bank boundaries. Hydraulic boundary distribution analyses confirm higher bed stress values in prismatic open channels. Shear stress in open channels represents the dragging force exerted by flowing water on boundaries. Velocity gradients and boundary geometry dictate local shear stress distribution across channel sections. Sediment transport calculations rely heavily on bed shear stress exceeding critical threshold values.
Channel design engineers must account for differential shear stress to prevent localized bed erosion. Unlined canals require protective lining on beds and banks based on expected boundary shear forces. River morphology studies analyze shear stress ratios to predict meandering and bank retreat patterns. Option a suggests bed shear is less than bank shear, which contradicts standard open channel hydraulics. Option b assumes uniform shear distribution, ignoring the geometric effects of sidewall boundaries. Option d is physically impossible since flowing water always exerts non-zero shear stresses on channel boundaries.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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