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Influencing river morphodynamics by means of bubble screens. Fundamentals and application to open-channel bends.

English title Influencing river morphodynamics by means of bubble screens. Fundamentals and application to open-channel bends.
Applicant Schleiss Anton
Number 125095
Funding scheme Project funding
Research institution Plateforme de constructions hydrauliques EPFL ENAC IIC PL-LCH
Institution of higher education EPF Lausanne - EPFL
Main discipline Fluid Dynamics
Start/End 01.10.2009 - 31.03.2013
Approved amount 182'030.00
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Keywords (10)

open-channel bend; meander; bubble screen; local scour; morphology; bubble plume; deposition; recirculating cell; ADVP; bubble-induced recirculating cell

Lay Summary (English)

Lead
Lay summary
Secondary flow in open-channel bends redistributes the velocities and the boundary shear stress and thereby creates variations in the bed topography. Outer banks are vulnerable to scouring whereas deposition near the bank may reduce the navigable width of the channel.Laboratory experiments in a sharply curved channel show that a secondary flow cell opposed to the curvature-induced secondary flow cell can be created near the outer bank by means of an air-bubble screen. The air bubbles coming from a porous tube installed on the bed rise to the water surface and thereby generate upwards flow, which drives the secondary flow cell.With respect to "hard" engineering techniques, bubble screens have the advantage of being controllable, ecological (oxygenation), reversible and non-permanent. They have already been applied in industrial, material, chemical, mechanical, and environmental applications, and abundantly investigated. According to literature, the application of bubble screens in river morphodynamics has not yet been investigated or applied in a systematic way.Comparison of reference experiments without bubble screen to experiments with bubble screen under similar conditions of water and sediment discharge may permit to estimate the influence of bubble screen on the bend morphology.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Influencing Flow Patterns and Bed Morphology in Open Channels and Rivers by Means of an Air-Bubble Screen
Dugué Violaine, Blanckaert Koen, Chen Qiuwen, Schleiss Anton (2015), Influencing Flow Patterns and Bed Morphology in Open Channels and Rivers by Means of an Air-Bubble Screen, in Journal of Hydraulic Engineering - ASCE, 141(2), 01014070-1-01014070-1.
A method for assessing the feasibility of air-bubble screens to reduce morphological gradients in open-channel bends
Dugué Violaine, Blanckaert Koen, Chen Qiuwen, Schleiss Anton (2013), A method for assessing the feasibility of air-bubble screens to reduce morphological gradients in open-channel bends, in Proceedings of the 35th IAHR World Congress, ChengduTsinghua University Press, Beijing.
Influencing River Morphodynamics by means of a bubble screen - Application to Open-Channel Bends
V. Dugué (2013), Influencing River Morphodynamics by means of a bubble screen - Application to Open-Channel Bends, Ecole Polytechnique Federale de Lausanne, PhD-thesis 5676.
Influencing river morphodynamics by means of a bubble screen: Application to open-channel bends
V. Dugué (2013), Influencing river morphodynamics by means of a bubble screen: Application to open-channel bends, Laboratoire de Constructions Hydrauliques, Ecole Polytechnique Federal de Lausanne, Lausanne, Switzerland.
Reduction of bend scour with an air-bubble screen - morphology and flow patterns
V. Dugué, K. Blanckaert, Q. Chen, A. J. Schleiss (2013), Reduction of bend scour with an air-bubble screen - morphology and flow patterns, in International Journal of Sediment Research, 28(1), 15-23.
An air-bubble screen used as a countermeasure to reduce erosion in open-channel bends
V. Dugué, K. Blanckaert, A. J. Schleiss (2012), An air-bubble screen used as a countermeasure to reduce erosion in open-channel bends, in Proceedings of the 6th International Conference on Scour and Erosion, Paris, FranceICSE, Paris.
Bend scour reduction induced by an air-bubble screen under live-bed conditions
V. Dugué, A. J. Schleiss, K. Blanckaert (2012), Bend scour reduction induced by an air-bubble screen under live-bed conditions, in Proceedings of River Flow 2012, San José, Costa RicaTaylor & Francis Group, London.
Flow patterns induced by a bubble screen in a sharply curved flume based on Acoustic Doppler Velocity Profiler
V. Dugué, K. Blanckaert, A. J. Schleiss (2012), Flow patterns induced by a bubble screen in a sharply curved flume based on Acoustic Doppler Velocity Profiler, in Proceedings of the 8th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics, Dresden, GermanyISUD, Dresden.
Preliminary study on the influence of an air-bubble screen on local scour around a bridge pier
V. Dugué, E. Izadinia, S. Rigaud, A. J. Schleiss (2012), Preliminary study on the influence of an air-bubble screen on local scour around a bridge pier, in Proceedings of the 2nd European IAHR Congress, Munich, GermanyIAHR, Munich.
Influencing bend morphodynamics by means of an air-bubble screen - Topography and velocity field
V. Dugué, K. Blanckaert, A. J. Schleiss (2011), Influencing bend morphodynamics by means of an air-bubble screen - Topography and velocity field, in Proceeding of the 7th IAHR Symposium on River, Coastal, Estuarine and Morphodynamics, Beijing, ChinaTsinghua University Press, Beijing.
Research on eco-hydro-morphological river processes by combining field investigations, physical modeling and numerical simulations
K. Blanckaert, W. van Balen, A. Duarte, V. Dugué, X. F. Garcia, W. Ottevanger, M. Pusch, A. M. Ricardo, I. Schnauder, V. Sukhodolov (2010), Research on eco-hydro-morphological river processes by combining field investigations, physical modeling and numerical simulations, in Proceedings of the International Symposium on Hydraulic Physical Modeling and Field Investigation, Nanjing, ChinaNHRI, Nanjing.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
35th IAHR World Congress Talk given at a conference A method for assessing the feasibility of air-bubble screens to reduce morphological gradients in open-channel bends. 08.09.2013 Chengdu, China Blanckaert Koen;
ISUD 2012 Talk given at a conference Flow patterns induced by a bubble screen in a sharply curved flume based on Acoustic Doppler Velocity Profiler measurements 19.09.2012 Dresden, Germany, Germany Dugué Violaine;
River Flow 2012 Talk given at a conference Bend scour reduction induced by an air-bubble screen under live-bed conditions 05.09.2012 San José, Costa Rica, Costa Rica Schleiss Anton; Dugué Violaine;
ISCE 2012 Talk given at a conference An air-bubble screen used as a countermeasure to reduce erosion in open-channel bends 27.08.2012 Paris, France, France Dugué Violaine;
IAHR Europe 2012 Talk given at a conference Preliminary Study on the Influence of an Air-Bubble Screen on Local Scour around a Bridge Pier 27.06.2012 Munich, Germany, Germany Schleiss Anton; Dugué Violaine;
RCEM 2011 Talk given at a conference Influencing bend morphodynamics by means of an air-bubble screen-Topography and velocity field 06.09.2011 Beijing, China, China Schleiss Anton; Dugué Violaine; Blanckaert Koen;


Associated projects

Number Title Start Funding scheme
119835 An experimental study on main flow, secondary flow and turbulence in open-channel bends with emphasis on their interaction with the outerbank geometry 01.04.2008 Project funding
103932 An experimental study on main flow, secondary flow and turbulence in open-channel bends with emphasis on their interaction with the outerbank geometry 01.08.2004 Project funding

Abstract

The interaction between velocity, boundary shear stress, sediment transport, sediment deposition and erosion and morphology in geophysical flows is often designated by the term morphodynamics. This proposal is part of a project that investigates how river morphodynamics can be influenced by means of bubble screens, which may be beneficial, for example, to reduce scour in open-channel bends and thereby increase the navigable width, reduce local scour around structures like bridge piers or abutment in open-channels, control reservoir sedimentation, prevent harbour silting.Bend scour, local scour and sedimentation can be attributed to vertically descending velocities impinging on the channel bed. Basically, the rising air-bubbles of the bubble screen counteract these descending velocities. With respect to "hard" engineering techniques, bubble screens have the advantage of being controllable, ecological (oxygenation), reversible and non-permanent. Bubble plumes and screens have been applied in industrial, material, chemical, mechanical, and environmental applications, and abundantly investigated. To our knowledge, the application of bubble screens in river morphodynamics has not yet been investigated or applied in a systematic way. Particularities of bubble screens in river morphodynamics are the shallowness of the flow and the interaction with the mobile bed.Preliminary experimental and numerical research, triggered by HKVconsultants and the RIZA department of the Dutch Ministry of Transport, Public Works and Water Management, has shown the feasibility of this bubble-screen technique to reduce scour in open-channel bends and increase the navigable width (see Annexe 3). The present project will carry out generic fundamental research on the use of bubble screens and subsequently focus on the application in open-channel bends. It will now be embedded in the framework of an ongoing joint research effort that exploits synergies between laboratory experiments at EPFL, field experiments at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB, Germany) and numerical modelling at Delft University of Technology (TUD, The Netherlands) (see chapter 4.1). It will benefit from this ongoing programme by adopting the same methodology (see chapter 4.1), using the same experimental and numerical facilities (see chapter 4.2.2), using available experimental data (see chapter 4.3), and being supervised by the same group. The present proposal concerning laboratory experiments at EPFL is self-contained, but will benefit from ongoing complementary numerical research at TUD and planned field experiments at IGB.Objectives of the project are:-Gaining insight in the processes underlying the bubble screen and the entrainment of flow in shallow configurations.-Defining guidelines for the numerical modelling of these processes.-Gaining insight in the interaction between bubble screen, flow, sediment transport and morphology in shallow free-surface flows, and in particular in open-channel bends.-Providing high-quality data that is appropriate for model validation.-Optimising the design of the planned pilot project in a natural river.Experiments without and with bubble screen will be carried out following a stepwise approach:-Experiments in shallow still water with fixed bed.-Experiments in shallow straight open channel flow with fixed horizontal bed and mobile bed.-Experiments in shallow curved open channel flow with fixed horizontal bed and mobile bed.
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