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| 1 | Two-phase air-water flows: Scale effects in physical modeling显示文摘Physical modeling represents probably the oldest design tool in hydraulic engineering together with analytical approaches. In free surface flows, the similitude based upon a Froude similarity allows for a correct representation of the dominant forces, namely gravity and inertia. As a result fluid flow properties such as the capillary forces and the viscous forces might be incorrectly reproduced, affecting the air entrainment and transport capacity of a high-speed model flow. Small physical models operating under a Froude similitude systematically underestimate the air entrainment rate and air-water interfacial properties. To limit scale effects, minimal values of Reynolds or Weber number have to be respected. The present article summarizes the physical background of such limitations and their combination in terms of the Morton number. Based upon a literature review, the existing limits are presented and discussed, resulting in a series of more conservative recommendations in terms of air concentration scaling. For other air-water flow parameters, the selection of the criteria to assess scale effects is critical because some parameters(e.g., bubble sizes, turbulent scales) can be affected by scale effects, even in relatively large laboratory models. | PFISTER Michael CHANSON Hubert | 2014 | Journal of Hydrodynamics2014，26，2： | 7 |
| 2 | Physical modelling and scale effects of air-water flows on stepped spillways显示文摘During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbu- lence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to pro- totypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels al- though little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein. | CHANSON Hubert GONZALEZ Carlos A. | 2005 | Journal of Zhejiang University-Science A(Applied Physics & Engineering)2005，6，3： | 5 |
| 3 | Turbulence and suspended sediment processes in the Garonne River tidal bore in November 2016显示文摘A tidal bore is a water discontinuity at the leading edge of a ood tide wave in estuaries with a large tidal range and funneling topography. New measurements were done in the Garonne River tidal bore on 14 15 November 2016, at a site previously investigated between 2010 and 2015. The data focused on long, continuous, high-frequency records of instantaneous velocity and suspended sediment con- centration (SSC) estimate for several hours during the late ebb, tidal bore passage and ood tide. The bore passage drastically modi ed the ow eld, with very intense turbulent and sediment mixing. This was evidenced with large and rapid uctuations of both velocity and Reynolds stress, as well as large SSCs during the ood tide. Granulometry data indicated larger grain sizes of suspended sediment in water samples compared to sediment bed material, with a broader distribution, shortly after the tidal bore. The tidal bore induced a sudden suspended sediment ux reversal and a large increase in suspended sedi- ment ux magnitude. The time-variations of turbulent velocity and suspended sediment properties indicated large uctuations throughout the entire data set. The ratio of integral time scales of SSC to velocity in the x-direction was on average TE,SSC/TE,x 0.16 during the late ebb tide, compared to TE,SSC/ TE,x 0.09 during the late ood tide. The results imply different time scales between turbulent velocities and suspended sediment concentrations. | David Reungoat Xinqian Leng Hubert Chanson | 2019 | International Journal of Sediment Research2019，34，5： | 5 |
| 4 | Bubble entrainment, spray and splashing at hydraulic jumps显示文摘The sudden transition from a high-velocity, supercritical open channel flow into a slow-moving sub-critical flow is a hydraulic jump. Such a flow is characterised by a sudden rise of the free-surface, with some strong energy dissipation and air entrainment, waves and spray. New two-phase flow measurements were performed in the developing flow region using a large-size facility operating at large Reynolds numbers. The experimental results demonstrated the complexity of the flow with a developing mixing layer in which entrained bubbles are advected in a high shear stress flow. The relationship between bubble count rates and void fractions was non-unique in the shear zone, supporting earlier observations of some form of double diffusion process between momentum and air bubbles. In the upper region, the flow consisted primarily of water drops and packets sur-rounded by air. Visually significant pray and splashing were significant above the jump roller. The present study is the first com-prehensive study detailing the two-phase flow properties of both the bubbly and spray regions of hydraulic jumps, a first step towards understanding the interactions between bubble entrainment and droplet ejection processes. | CHANSON Hubert | 2006 | Journal of Zhejiang University-Science A(Applied Physics & Engineering)2006，7，8： | 2 |
| 5 | Air-water gas transfer at hydraulic jump with partially developed inflow显示文摘 | Hubert Chanson | 1995 | Water Res1995，29，10： | 1 |
| 6 | Energy dissipation on stepped spillways and hydraulic challenges—Prototype and laboratory experiences显示文摘Stepped cascades, chutes and spillways have been in use for more than three millennia. With the introduction of new construction materials and techniques, the staircase chute design has regained some interest within the last forty years. The stepped invert increases significantly the energy dissipation occurring above the steep chute and reduces the size of the required downstream stilling structure. The application of stepped chutes further encompasses in-stream re-aeration and water treatment plant cascades, to enhance the air-water transfer of atmospheric gases and of volatile organic components. However, the engineering design of stepped spillways is not simple because of the hydrodynamic challenges, with several markedly different flow regimes, some complicated two-phase air-water fluid dynamics and massive rate of energy dissipation above the stepped chute. Simply, the technical challenges in the hydraulic design of stepped spillways are massive. This review paper examines the hydraulic characteristics of stepped chute flows and develops a reflection on nearly three decades of active hydraulic research, including recent field measurements during major flood events. The author aims to share his passion for the complicated hydraulic engineering, as well as some advice for engineering professionals and researchers. | Hubert Chanson | 2022 | Journal of Hydrodynamics2022，34，1： | 1 |
| 7 | Acoustic Doppler velocimetry (ADV) in small estuary: Field experience and signal post-processing显示文摘 | Chanson Hubert Trevethan Mark Aoki Shin-iehi | 2008 | Flow Measurement and Instrumentation2008，19，5： | 1 |
| 8 | Hydraulics of skimming flows over stepped channels and spillways显示文摘 | Chanson Hubert | 1994 | Journal of Hydraulic Research JAHR1994，32，3： | 1 |
| 9 | Advanced post-processing and correlation analyses in high-velocity air–water flows显示文摘 | Hubert Chanson Giovanna Carosi | 2007 | Environmental Fluid Mechanics2007，，6： | 1 |
| 10 | Turbulent time and length scale measurements in high-velocity open channel flows显示文摘 | Hubert Chanson Giovanna Carosi | 2007 | Experiments in Fluids2007，，3： | 1 |
| 11 | Measuring air-water interface area in supercritical open channel flow显示文摘 | Hubert Chanson | 1997 | Water Research1997，31，6： | 1 |
| 12 | Current knowledge in hydraulic jumps and related phenomena 显示文摘 | Hubert Chanson | 2009 | European Journal of Mechanics B/Fluids2009，28，2： | 1 |
| 13 | Physical Modeling of the Flow Field in an Undular Tidal Bore 显示文摘 | Hubert Chanson | 2005 | Journal of Hydraulic Research (S0022-1686)2005，43，3： | 1 |
| 14 | EXTREME RESERVOIR SEDIMENTATION IN AUSTRALIA : A REVIEW显示文摘EXTREMERESERVOIRSEDIMENTATIONINAUSTRALIA:AREVIEWHubertCHANSON1ABSTRACTInthepaper,theauthorreviewstheproblemofreservoirsiltati... | Hubert CHANSON 1 | 1998 | International Journal of Sediment Research1998，13，3： | 0 |
| 15 | Aeration performances and air—Water mass transfer on steep stepped weirs with horizontal and inclined steps显示文摘At hydraulic structures,some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the flow.In turn,in-stream structures may contribute to the aeration and re-oxygenation during overflow.The present study aims to characterize the aeration performance of a steep stepped weir,based upon a detailed physical investigation of air-water interfacial properties across a relatively wide range of discharges.The data showed a strong fragmentation of the air-water flows,a very broad range of entrained bubbles and drops,and a large amount of particle clustering.The results implied a monotonic increase in re-aeration with increasing rate of energy dissipation,while the largest aeration efficiency was observed on the horizontal step weir chute,with the smallest on the 1V:2.33H inclined downward steps.Altogether,the study showed that a steep stepped chute can make a sizeable contribution to the re-oxygenation of the waters,although the downward inclined steps reduce the re-aeration performances. | Yvan Arosquipa Nina Rui Shi Davide Wüthrich Hubert Chanson | 2022 | Journal of Hydrodynamics2022，34，5： | 0 |
| 16 | 小型亚热带半日潮河口中的湍流显示文摘在天然河口,污染物的输送是由湍流动量混合驱动的,而弥散的大小却难以被准确地预测。这是由于对河口的湍流结构缺乏基础的认识而造成的。介绍在一个小型的亚热带半日潮河口进行的高频率及连续50 h的湍流实地测量的情况。在研究的浅水(低潮水深小于0.5 m)小型河口中,使用了最适用于这种水体的声学多普勒流速仪进行测量,并进行了完整的后处理工作。河口水流是一个波动的过程,各种宏观流动参数随潮周期和其它大尺度的过程而波动,但是湍流特性是由即时局部流动特性所决定,它们基本不受流动历程的影响,其结构和瞬时变化受多种机理影响。这导致其只与水流剪切力引起的湍流边界层平衡相关。所有湍流特性在潮周期中均有大波动是本次研究数据的一个显著特征,这一特征在此前少有记载,但本次的测量数据与过往数据的一大差别是,数据连续测量的时间长且频率高。这将为波动特性的动量交换系数及积分时间和长尺度提供新的信息,这些湍流特性不应被视为不变的。 | Hubert CHANSON Mark TREVETHAN 萧洁儿(翻译) | 2007 | 人民珠江2007，28，1： | 0 |
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