Flow resistance over duned channel bed

• Main Author: Widjaja, Richard
• Other Authors: Cheng Niansheng
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/75114
• Institution: Nanyang Technological University

Current water demand in Singapore is about 430 million gallons per day, with 45% coming from domestic sector and 55% from non-domestic. Four water sources: NEWater, desalinated water, water from local catchment and imported water, have been developed by the Singapore government to fulfil this demand. To maximize the water from local catchment, a study about waterways which functions to transport rainwater to the nearest catchment is needed. One of the common problems that is encountered in natural waterways is the presence of big gravels or dunes that obstruct the flow. Many previous studies have been conducted to investigate the effects of numerous flow and geometric parameters on the dune resistance. However, there is insufficient data which can be used to satisfactorily describe the dune friction factor. In this study, a series of experimental studies were conducted to investigate flow resistance over fixed dunes. In addition, a formula was also derived based on energy loss in the flow to calculate the friction factor and was compared to the Darcy-Weisbach equation. It was found that the proposed formula was not applicable for some cases. Therefore, to investigate other parameters that might affect the friction factor, five parameters, Reynolds number, Froude number, bed slope, dune coefficient and type of dune, were chosen to be plotted against the friction factor. In conclusion, Reynolds number has negligible effect on the friction factor at high velocity. On the other hand, the friction factor decreases when Froude number increases. Slope is proportional to the resistance while friction factor decreases with dune coefficient.