IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 5 - FLUVIAL HYDRAULICS AND RIVER MANAGEMENT : Suction Effects on Flow Behavior and Sediment Transport in Closed-conduit Flows
Suction Effects on Flow Behavior and Sediment Transport in Closed-conduit Flows
Author : Cao Deping and Chiew Yee-Meng
Many studies have been carried out to investigate suction effects on flow behaviour and sediment transport. Published literature has shown that suction has a significant impact on bed erosion and deposition in a fluvial system. In the present study, experiments are conducted to investigate suction effects on sediment transport in a 9 m long closed conduit with a 50-cm long zone that is subjected to uniform suction. Cohesionless sediment particles with medium diameter = 0.80 mm were used in the study. A 50-cm long sediment recess with a sand trap is constructed to collect the sand transported from the suction zone in the experiments, allowing the amount of sand transported to be measured directly. The results show that an increase in suction rate leads to an increase in bedload transport rate. The results are consistent with some published results of suction effects on sediment transport in open channel flow. A possible explanation is proposed to account for the reason of increasing q with increasing suction rate. b Increasing suction rate leads to both increasing horizontal velocity u and vertical velocity v at the bed b b level. It is, therefore, surmised that increasing u will increase the drag force, causing the sediment b particles to move more easily or faster while increasing v will increase the frictional force between b particles, thus decelerate sediment transport rate. To verify this explanation, the Particle Image Velocimetry (PIV) was used to measure the flow behavior with different suction rates in this study. The experimental measurement shows that both the horizontal and vertical approach velocities increase with increasing suction rates. Suction effects on turbulence characteristics are also investigated; the data show that turbulence increases with increasing suction rate when suction rate is within a certain range and decreases beyond that range.
File Size : 2,314,429 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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