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E-Thesis 707 views

Computational Investigation of Flow over Gabion Spillways / Ali A. A. Zuhaira

Swansea University Author: Ali A. A. Zuhaira

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DOI (Published version): 10.23889/SUthesis.40796

Abstract

A spillway is a hydraulic structure that is used to pass high discharges in flood seasons in a controlled way and also to release surplus water that cannot be safely stored in the reservoir to downstream. Stepped spillways and gabion stepped spillways have been used for centuries as an effective and...

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Published: 2018
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa40796
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first_indexed 2018-06-22T19:37:07Z
last_indexed 2020-09-02T03:04:47Z
id cronfa40796
recordtype RisThesis
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spelling 2020-09-01T16:21:40.4271183 v2 40796 2018-06-22 Computational Investigation of Flow over Gabion Spillways 21c9f21261f98463862efc079b092229 NULL Ali A. A. Zuhaira Ali A. A. Zuhaira true true 2018-06-22 A spillway is a hydraulic structure that is used to pass high discharges in flood seasons in a controlled way and also to release surplus water that cannot be safely stored in the reservoir to downstream. Stepped spillways and gabion stepped spillways have been used for centuries as an effective and efficient way of dissipating the energy of overflowing water. The steps of the spillway’s surface increase its roughness and therefore can generate high turbulence levels. Three main flow regimes can be identified over stepped spillways; namely nappe, transition and skimming flow depending on step size and water discharge. Under skimming flow conditions, the aerated and non-aerated flow regions can be clearly recognised over the chute slope depending on the air content.Investigation of the hydraulics of skimming flow conditions over gabion stepped spillways have been exclusively experimental to date, and have concentrated on the aerated zone under skimming flow conditions. Our knowledge of the flow properties in the non-aerated flow region over gabion steps is lacking and further research is required to improve the hydraulic structure design. This thesis describes the research undertaken to address this need.It is primarily a computational study but includes some experimental work for model validation. The numerical code is initially validated against different laboratory experimental data. The results indicated that the numerical code is robust in predicting flow field variables over gabion stepped spillways. The validated code is then applied to different cases of gabion stepped spillways, to explore the behaviour of the skimming flow with various step heights, chute slopes and step shapes. This work provides new insights into the hydraulics of skimming flow conditions in the non-aerated flow region over gabion stepped spillways. The computational results of this study have important implications for designing gabion stepped chutes, such as determining the position of free surface aeration and optimum step configuration. E-Thesis embankment dams, gabion stepped spillways, stepped spillways, numerical simulation, PIV experiments 31 12 2018 2018-12-31 10.23889/SUthesis.40796 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D The Higher Committee for Education Development in Iraq (HCED) 2020-09-01T16:21:40.4271183 2018-06-22T14:13:28.5429743 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Ali A. A. Zuhaira NULL 1 Under embargo Under embargo 2018-06-22T14:15:34.9670000 Output 14811578 application/pdf Redacted version - open access true 2023-06-25T00:00:00.0000000 A selection of third party content is redacted or is partially redacted from this thesis. true
title Computational Investigation of Flow over Gabion Spillways
spellingShingle Computational Investigation of Flow over Gabion Spillways
Ali A. A. Zuhaira
title_short Computational Investigation of Flow over Gabion Spillways
title_full Computational Investigation of Flow over Gabion Spillways
title_fullStr Computational Investigation of Flow over Gabion Spillways
title_full_unstemmed Computational Investigation of Flow over Gabion Spillways
title_sort Computational Investigation of Flow over Gabion Spillways
author_id_str_mv 21c9f21261f98463862efc079b092229
author_id_fullname_str_mv 21c9f21261f98463862efc079b092229_***_Ali A. A. Zuhaira
author Ali A. A. Zuhaira
author2 Ali A. A. Zuhaira
format E-Thesis
publishDate 2018
institution Swansea University
doi_str_mv 10.23889/SUthesis.40796
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 0
active_str 0
description A spillway is a hydraulic structure that is used to pass high discharges in flood seasons in a controlled way and also to release surplus water that cannot be safely stored in the reservoir to downstream. Stepped spillways and gabion stepped spillways have been used for centuries as an effective and efficient way of dissipating the energy of overflowing water. The steps of the spillway’s surface increase its roughness and therefore can generate high turbulence levels. Three main flow regimes can be identified over stepped spillways; namely nappe, transition and skimming flow depending on step size and water discharge. Under skimming flow conditions, the aerated and non-aerated flow regions can be clearly recognised over the chute slope depending on the air content.Investigation of the hydraulics of skimming flow conditions over gabion stepped spillways have been exclusively experimental to date, and have concentrated on the aerated zone under skimming flow conditions. Our knowledge of the flow properties in the non-aerated flow region over gabion steps is lacking and further research is required to improve the hydraulic structure design. This thesis describes the research undertaken to address this need.It is primarily a computational study but includes some experimental work for model validation. The numerical code is initially validated against different laboratory experimental data. The results indicated that the numerical code is robust in predicting flow field variables over gabion stepped spillways. The validated code is then applied to different cases of gabion stepped spillways, to explore the behaviour of the skimming flow with various step heights, chute slopes and step shapes. This work provides new insights into the hydraulics of skimming flow conditions in the non-aerated flow region over gabion stepped spillways. The computational results of this study have important implications for designing gabion stepped chutes, such as determining the position of free surface aeration and optimum step configuration.
published_date 2018-12-31T03:51:56Z
_version_ 1763752560037986304
score 11.014067

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