A generalized study of local scour downstream of a weir

This research examined the critical parameters affecting the equilibrium scour depth at the downstream of an overflowing weir. A generalized prediction equation, based on the experiments in this study and data from previous FYP studies. has been proposed. The key variables involved in the formula ar...

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Main Author: Hiew, Wing Yian
Other Authors: Lim Siow Yong
Format: Final Year Project
Language:English
Published: Nanyang Technological University 2024
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Online Access:https://hdl.handle.net/10356/176252
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1762522024-05-17T15:34:50Z A generalized study of local scour downstream of a weir Hiew, Wing Yian Lim Siow Yong School of Civil and Environmental Engineering CSYLIM@ntu.edu.sg Engineering Hydraulics Scour Scouring Dimensional analysis Regression analysis Water resource Weir Apron This research examined the critical parameters affecting the equilibrium scour depth at the downstream of an overflowing weir. A generalized prediction equation, based on the experiments in this study and data from previous FYP studies. has been proposed. The key variables involved in the formula are the weir height, flow rate, tailwater depth, and median sediment size. This study comprises two primary phases: the literature review and data collection phase followed by the experiment and data analysis phase. Phase 1: Past research works on weir scour such as Veronese’s early study in 1937, NTU’s extensive FYP data and relevant field data have been reviewed and analysed. Phase 2: Employing a hydraulic flume at the NTU laboratory, the real-world hydraulic conditions for a weir scour were studied through hands-on experiments. In this study, sediment diameters and weir height are selected as control variables, whereas tailwater depth and flowrate are the independent variables that are meticulously varied to investigate the gap and grasp the intricacies of the correlation and interplay among the parameters, which has not been examined closely in previous NTU experiments. This research found that the Shield parameters and eddies formation as well as secondary current observed in the scour hole should not be ignored for a more accurate scour prediction. The Shield parameter in the form of a densimetric Froude number is recognized as the most influential flow parameter from data analysis and the weir height is identified as the most effective length scale from the result of all researches conducted at NTU. Based on dimensional analysis and multiple regression analysis, a prediction equation was derived and was then compared using 36 previous non-NTU laboratory data with very small scour hole, 12 field data and 62 NTU obtained from well-controlled experiments followed by validation with very large-scale real-world data at Arno River with an overprediction of 43.9% and a satisfying correlation coefficient of R2=0.83. The reasonable rate of overprediction achieves a good balance between being safe and conservative in practice. Bachelor's degree 2024-05-17T06:25:34Z 2024-05-17T06:25:34Z 2024 Final Year Project (FYP) Hiew, W. Y. (2024). A generalized study of local scour downstream of a weir. Final Year Project (FYP), Nanyang Technological University, Singapore. https://hdl.handle.net/10356/176252 https://hdl.handle.net/10356/176252 en application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering
Hydraulics
Scour
Scouring
Dimensional analysis
Regression analysis
Water resource
Weir
Apron
spellingShingle Engineering
Hydraulics
Scour
Scouring
Dimensional analysis
Regression analysis
Water resource
Weir
Apron
Hiew, Wing Yian
A generalized study of local scour downstream of a weir
description This research examined the critical parameters affecting the equilibrium scour depth at the downstream of an overflowing weir. A generalized prediction equation, based on the experiments in this study and data from previous FYP studies. has been proposed. The key variables involved in the formula are the weir height, flow rate, tailwater depth, and median sediment size. This study comprises two primary phases: the literature review and data collection phase followed by the experiment and data analysis phase. Phase 1: Past research works on weir scour such as Veronese’s early study in 1937, NTU’s extensive FYP data and relevant field data have been reviewed and analysed. Phase 2: Employing a hydraulic flume at the NTU laboratory, the real-world hydraulic conditions for a weir scour were studied through hands-on experiments. In this study, sediment diameters and weir height are selected as control variables, whereas tailwater depth and flowrate are the independent variables that are meticulously varied to investigate the gap and grasp the intricacies of the correlation and interplay among the parameters, which has not been examined closely in previous NTU experiments. This research found that the Shield parameters and eddies formation as well as secondary current observed in the scour hole should not be ignored for a more accurate scour prediction. The Shield parameter in the form of a densimetric Froude number is recognized as the most influential flow parameter from data analysis and the weir height is identified as the most effective length scale from the result of all researches conducted at NTU. Based on dimensional analysis and multiple regression analysis, a prediction equation was derived and was then compared using 36 previous non-NTU laboratory data with very small scour hole, 12 field data and 62 NTU obtained from well-controlled experiments followed by validation with very large-scale real-world data at Arno River with an overprediction of 43.9% and a satisfying correlation coefficient of R2=0.83. The reasonable rate of overprediction achieves a good balance between being safe and conservative in practice.
author2 Lim Siow Yong
author_facet Lim Siow Yong
Hiew, Wing Yian
format Final Year Project
author Hiew, Wing Yian
author_sort Hiew, Wing Yian
title A generalized study of local scour downstream of a weir
title_short A generalized study of local scour downstream of a weir
title_full A generalized study of local scour downstream of a weir
title_fullStr A generalized study of local scour downstream of a weir
title_full_unstemmed A generalized study of local scour downstream of a weir
title_sort generalized study of local scour downstream of a weir
publisher Nanyang Technological University
publishDate 2024
url https://hdl.handle.net/10356/176252
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