While the hydraulic mean depth (Dm) for a full circular pipe of diameter ‘D’ is 0.25 D, a circular channel reaches Dm = 0.3 D under the condition of maximum ?
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Answer: B. Mean velocity
Explanation
Maximum mean velocity in a circular open channel occurs at a specific partial filling depth. At this optimal depth, the hydraulic mean depth reaches approximately 0.3 D. Friction and area interactions peak to maximize velocity just below the pipe crown. Hydraulic mean depth is the ratio of flow area to top water surface width. Open channel flow velocity depends on channel slope, roughness, and hydraulic radius. Flowing completely full yields a hydraulic mean depth of 0.25 D for circular pipes.
Sanitary sewer designers utilize partial flow curves to prevent sediment deposition by maintaining velocity. Stormwater drainage systems are analyzed using maximum velocity and discharge criteria. Understanding these depth ratios ensures optimal conveyance capacity in circular conduits. Maximum flow rate in circular channels actually occurs at approximately 0.93 D rather than 0.3 D. Claiming neither flow rate nor mean velocity is correct ignores established open channel hydraulics. Selecting only flow rate confuses the distinct depths required for maximum velocity versus discharge.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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