Flow development in rough-bed open channels

Andrea Zampiron; Stuart Cameron; Mark Stewart; Vladimir Nikora

doi:10.3850/IAHR-39WC252171192022444

Flow development in rough-bed open channels

Andrea Zampiron^* (Corresponding Author), Stuart Cameron, Mark Stewart, Vladimir Nikora

^*Corresponding author for this work

Engineering

Research output: Chapter in Book/Report/Conference proceeding › Published conference contribution

Abstract

In open-channel flows, one of the main assumptions is of fully developed flow, which means that flow parameters do not change in the streamwise direction. The question then is: what distance from the flume entrance is required to achieve fully developed flow conditions? The available data are not sufficient to answer this question properly, and researchers often employ some rather intuitive approximations instead of tailored preliminary measurements. This paper assesses the development of the flow in two different facilities using a combination of stereoscopic particle-image velocimetry and acoustic Doppler velocimetry data sets covering a range of flow conditions and bed roughness. It is found that while some turbulence features are essentially fully developed within 100 flow depths from the channel entrance (i.e., mean velocity, Reynolds stresses, and large-scale motions), others require distances up to 150 (i.e., streamwise turbulent variance and very large-scale motions).

Original language	English
Title of host publication	Proceedings of the 39th IAHR World Congress
Subtitle of host publication	From Snow to Sea
Publisher	IAHR
Pages	5025-5029
Number of pages	5
ISBN (Print)	978-90-832612-1-8
DOIs	https://doi.org/10.3850/IAHR-39WC252171192022444
Publication status	Published - 19 Jun 2022
Event	39th IAHR World Congress, 2022 - Granada, Spain Duration: 19 Jun 2022 → 24 Jun 2022

Publication series

Name	Proceedings of the IAHR World Congress
ISSN (Print)	2521-7119
ISSN (Electronic)	2521-716X

Conference

Conference	39th IAHR World Congress, 2022
Country/Territory	Spain
City	Granada
Period	19/06/22 → 24/06/22

Bibliographical note

Funding Information:
The authors wish to express their gratitude to Roy Gillanders for the help provided. Financial support was provided by three EPSRC/UK grants: ‘High-resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport’ (EP/G056404/1), ‘Bed friction in rough-bed free-surface flows: a theoretical framework, roughness regimes, and quantification’ (EP/K041088/1) and ‘Secondary currents in turbulent flows over rough walls’ (EP/V002414/1).

Keywords

Flow development
Hydraulic experiments
Open-channel flow
Turbulence
Very-large-scale motions

Access to Document

10.3850/IAHR-39WC252171192022444Licence: Unspecified

Cite this

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title = "Flow development in rough-bed open channels",

abstract = "In open-channel flows, one of the main assumptions is of fully developed flow, which means that flow parameters do not change in the streamwise direction. The question then is: what distance from the flume entrance is required to achieve fully developed flow conditions? The available data are not sufficient to answer this question properly, and researchers often employ some rather intuitive approximations instead of tailored preliminary measurements. This paper assesses the development of the flow in two different facilities using a combination of stereoscopic particle-image velocimetry and acoustic Doppler velocimetry data sets covering a range of flow conditions and bed roughness. It is found that while some turbulence features are essentially fully developed within 100 flow depths from the channel entrance (i.e., mean velocity, Reynolds stresses, and large-scale motions), others require distances up to 150 (i.e., streamwise turbulent variance and very large-scale motions).",

keywords = "Flow development, Hydraulic experiments, Open-channel flow, Turbulence, Very-large-scale motions",

author = "Andrea Zampiron and Stuart Cameron and Mark Stewart and Vladimir Nikora",

note = "Funding Information: The authors wish to express their gratitude to Roy Gillanders for the help provided. Financial support was provided by three EPSRC/UK grants: {\textquoteleft}High-resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport{\textquoteright} (EP/G056404/1), {\textquoteleft}Bed friction in rough-bed free-surface flows: a theoretical framework, roughness regimes, and quantification{\textquoteright} (EP/K041088/1) and {\textquoteleft}Secondary currents in turbulent flows over rough walls{\textquoteright} (EP/V002414/1). ; 39th IAHR World Congress, 2022 ; Conference date: 19-06-2022 Through 24-06-2022",

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AU - Zampiron, Andrea

AU - Cameron, Stuart

AU - Stewart, Mark

AU - Nikora, Vladimir

N1 - Funding Information: The authors wish to express their gratitude to Roy Gillanders for the help provided. Financial support was provided by three EPSRC/UK grants: ‘High-resolution numerical and experimental studies of turbulence-induced sediment erosion and near-bed transport’ (EP/G056404/1), ‘Bed friction in rough-bed free-surface flows: a theoretical framework, roughness regimes, and quantification’ (EP/K041088/1) and ‘Secondary currents in turbulent flows over rough walls’ (EP/V002414/1).

PY - 2022/6/19

Y1 - 2022/6/19

N2 - In open-channel flows, one of the main assumptions is of fully developed flow, which means that flow parameters do not change in the streamwise direction. The question then is: what distance from the flume entrance is required to achieve fully developed flow conditions? The available data are not sufficient to answer this question properly, and researchers often employ some rather intuitive approximations instead of tailored preliminary measurements. This paper assesses the development of the flow in two different facilities using a combination of stereoscopic particle-image velocimetry and acoustic Doppler velocimetry data sets covering a range of flow conditions and bed roughness. It is found that while some turbulence features are essentially fully developed within 100 flow depths from the channel entrance (i.e., mean velocity, Reynolds stresses, and large-scale motions), others require distances up to 150 (i.e., streamwise turbulent variance and very large-scale motions).

AB - In open-channel flows, one of the main assumptions is of fully developed flow, which means that flow parameters do not change in the streamwise direction. The question then is: what distance from the flume entrance is required to achieve fully developed flow conditions? The available data are not sufficient to answer this question properly, and researchers often employ some rather intuitive approximations instead of tailored preliminary measurements. This paper assesses the development of the flow in two different facilities using a combination of stereoscopic particle-image velocimetry and acoustic Doppler velocimetry data sets covering a range of flow conditions and bed roughness. It is found that while some turbulence features are essentially fully developed within 100 flow depths from the channel entrance (i.e., mean velocity, Reynolds stresses, and large-scale motions), others require distances up to 150 (i.e., streamwise turbulent variance and very large-scale motions).

KW - Flow development

KW - Hydraulic experiments

KW - Open-channel flow

KW - Turbulence

KW - Very-large-scale motions

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ER -

Flow development in rough-bed open channels

Abstract

Publication series

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Bibliographical note

Keywords

Access to Document

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