TY  - JOUR
A1  - Bung, Daniel B.
A1  - Valero, Daniel
T1  - Re-aeration on stepped spillways with special consideration of entrained and entrapped air
JF  - Geosciences
N2  - As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.
Y1  - 2018
SN  - 2076-3263
VL  - 8
IS  - 9
SP  - Article number 333
PB  - MDPI
CY  - Basel
ER  - 
TY  - CHAP
A1  - Bung, Daniel B.
A1  - Valero, Daniel
A1  - Hermens, G.
T1  - Hybrid investigation on the hydraulic performance of a new trapezoidal fishway
T2  - 7th IAHR International Symposium on Hydraulic Structures, ISHS 2018
Y1  - 2018
SN  - 978-069213277-7
U6  - http://dx.doi.org/10.15142/T3S06R
SP  - 184
EP  - 193
ER  - 
TY  - JOUR
A1  - Kramer, Matthias
A1  - Valero, Daniel
A1  - Chanson, Hubert
A1  - Bung, Daniel B.
T1  - Towards reliable turbulence estimations with phase-detection probes: an adaptive window cross-correlation technique
JF  - Experiments in Fluids
Y1  - 2019
U6  - http://dx.doi.org/10.1007/s00348-018-2650-9
SN  - 1432-1114
VL  - 60
EP  - Article number 2
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Chanson, Hubert
A1  - Bung, Daniel B.
T1  - Robust estimators for turbulence properties assessment
Y1  - 2019
SP  - 1
EP  - 24
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Chanson, Hubert
A1  - Bung, Daniel B.
T1  - Robust estimators for free surface turbulence characterization: A stepped spillway application
JF  - Flow Measurement and Instrumentation
N2  - Robust estimators are parameters insensitive to the presence of outliers. However, they presume the shape of the variables’ probability density function. This study exemplifies the sensitivity of turbulent quantities to the use of classic and robust estimators and the presence of outliers in turbulent flow depth time series. A wide range of turbulence quantities was analysed based upon a stepped spillway case study, using flow depths sampled with Acoustic Displacement Meters as the flow variable of interest. The studied parameters include: the expected free surface level, the expected fluctuation intensity, the depth skewness, the autocorrelation timescales, the vertical velocity fluctuation intensity, the perturbations celerity and the one-dimensional free surface turbulence spectrum. Three levels of filtering were utilised prior to applying classic and robust estimators, showing that comparable robustness can be obtained either using classic estimators together with an intermediate filtering technique or using robust estimators instead, without any filtering technique.
Y1  - 2020
U6  - http://dx.doi.org/10.1016/j.flowmeasinst.2020.101809
SN  - 0955-5986
VL  - 76
IS  - Art. 101809
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Valero, Daniel
A1  - Kramer, Matthias
A1  - Bung, Daniel B.
A1  - Chanson, Hubert
T1  - A stochastic bubble generator for air-water flow research
T2  - E-proceedings of the 38th IAHR World Congress, September 1-6, 2019, Panama City, Panama
Y1  - 2019
U6  - http://dx.doi.org/10.3850/38WC092019-0909
SP  - 5714
EP  - 5721
ER  - 
TY  - JOUR
A1  - Bung, Daniel B.
A1  - Crookston, Brian M.
A1  - Valero, Daniel
T1  - Turbulent free-surface monitoring with an RGB-D sensor: the hydraulic jump case
JF  - Journal of Hydraulic Research
Y1  - 2020
U6  - http://dx.doi.org/10.1080/00221686.2020.1844810
SN  - 1814-2079
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Schalko, Isabella
A1  - Friedrich, Heide
A1  - Abad, Jorge D.
A1  - Bung, Daniel B.
A1  - Donchyts, Gennadii
A1  - Felder, Stefan
A1  - Ferreira, Rui M. L.
A1  - Hohermuth, Benjamin
A1  - Kramer, Matthias
A1  - Li, Danxun
A1  - Mendes, Luis
A1  - Moreno-Rodenas, Antonio
A1  - Nones, Michael
A1  - Paron, Paolo
A1  - Ruiz-Villanueva, Virginia
A1  - Wang, Ruo-Qian
A1  - Franca, Mario J.
T1  - Pathways towards democratization of hydro-environment observations and data
JF  - Iahr White Paper Series
Y1  - 2021
IS  - 1
SP  - 1
EP  - 9
PB  - International Association for Hydro-Environment Engineering and Research (IAHR)
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Bung, Daniel B.
A1  - Erpicum, Sebastien
A1  - Peltier, Yann
A1  - Dewals, Benjamin
T1  - Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling
JF  - Journal of Hydro-environment Research
N2  - Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models).
KW  - coherent structures
KW  - hydraulic modelling
KW  - model performance
KW  - Proper Orthogonal Decomposition
KW  - Q-criterion
Y1  - 2022
U6  - http://dx.doi.org/10.1016/j.jher.2022.03.002
SN  - 1570-6443
IS  - In Press
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bung, Daniel B.
A1  - Valero, Daniel
T1  - Optical flow estimation in aerated flows
JF  - Journal of Hydraulic Research
N2  - Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.
Y1  - 2016
U6  - http://dx.doi.org/10.1080/00221686.2016.1173600
VL  - 54
IS  - 5
SP  - 575
EP  - 580
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - CHAP
A1  - Kerpen, N. B.
A1  - Bung, Daniel B.
A1  - Schlurmann, Torsten
ED  - Janssen, Robert
T1  - Physical model investigations of ships passing through a lock
T2  - Hydraulic structures: useful water harvesting systems or relics? : Third International Junior Researcher and Engineer Workshop on Hydraulic Structures (IJREWHS'10) : Edinburgh, Scotland, U.K., 2-3 May 2010
Y1  - 2010
SN  - 9781742720159
SP  - 93
EP  - 100
PB  - School of Civil Engineeering, The University of Queensland
CY  - Brisbane
ER  - 
TY  - CHAP
A1  - Kerpen, N. B.
A1  - Bung, Daniel B.
A1  - Schlurmann, Torsten
T1  - Physical model investigations of pressure distributions next to ships passing through a lock
T2  - 5th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : CG JOINT 2010
Y1  - 2010
SN  - 978-7-5618-3671-2
SP  - 514
EP  - 519
PB  - Univ. Press
CY  - Tianjin
ER  - 
TY  - BOOK
A1  - Bleninger, T.
A1  - Brenda, M.
A1  - Bung, Daniel B.
A1  - Hengl, M.
A1  - Schmid, B.H.
A1  - Schneider, E.
A1  - Sonnenburg, A.
A1  - Stoschek, O.
T1  - DWA-Regelwerk M 544-1 : Merkblatt: Ausbreitungsprobleme von Einleitungen - Prozesse, Methoden und Modelle - Teil 1: Anwendungsgrundlagen, Schätzformeln und eindimensionale Modelle
Y1  - 2016
SN  - 978-3-88721-280-3
CY  - Hennef
ER  - 
TY  - BOOK
A1  - Bleninger, T.
A1  - Brenda, M.
A1  - Bung, Daniel B.
A1  - Hengl, M.
A1  - Schmid, B.H.
A1  - Schneider, E.
A1  - Sonnenburg, A.
A1  - Stoschek, O.
T1  - DWA-Regelwerk M 544-2 : Merkblatt: Ausbreitungsprobleme von Einleitungen - Prozesse, Methoden und Modelle - Teil 2: Mehrdimensionale Modelle
Y1  - 2016
SN  - 978-3-88721-281-0
CY  - Hennef
ER  - 
TY  - JOUR
A1  - Valero, D.
A1  - Bung, Daniel B.
A1  - Crookston, B. M.
T1  - Closure to “Energy Dissipation of a Type III Basin under Design and Adverse Conditions for Stepped and Smooth Spillways”
JF  - Journal of Hydraulic Engineering
Y1  - 2019
U6  - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001669
VL  - 146
IS  - 2
PB  - ASCE
CY  - Reston, Va.
ER  - 
TY  - CHAP
A1  - Oertel, Mario
A1  - Bung, Daniel B.
A1  - Schlenkhoff, Andreas
ED  - Carstensen, Dirk
T1  - Blocksteinrampen in Riegelbauweise : Neue Bemessungsansätze
T2  - Staubauwerke : planen, bauen, betreiben; 35. Dresdner Wasserbaukolloquium 2012, 08. - 09. März 2012
Y1  - 2012
SN  - 978-3-86780-261-1
SP  - 317
EP  - 326
PB  - Selbstverl. der Techn. Univ.
CY  - Dresden
ER  - 
TY  - JOUR
A1  - Bung, Daniel B.
T1  - Non-intrusive detection of air–water surface roughness in self-aerated chute flows
JF  - Journal of hydraulic research
Y1  - 2013
SN  - 1814-2079 (E-Journal); 0022-1686 (Print)
VL  - Vol. 51
IS  - Iss. 3
SP  - 322
EP  - 329
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - CHAP
A1  - Bung, Daniel B.
A1  - Pagliara, S.
T1  - Proceedings of the International Workshop on Hydraulic Design of Low-Head Structures : Aachen, Germany, February, 20-22, 2013 /  D. Bung ; S. Pagliara (eds.)
Y1  - 2013
SN  - 978-3-939230-04-5
PB  - Bundesanst. für Wasserbau
CY  - Karlsruhe
ER  - 
TY  - JOUR
A1  - Oertel, Mario
A1  - Bung, Daniel B.
T1  - Initial stage of two-dimensional dam-break waves: laboratory versus VOF
JF  - Journal of hydraulic research
N2  - Since several decades, dam-break waves have been of main research interest. Mathematical approaches have been developed by analytical, physical and numerical models within the past 120 years. During the past 10 years, the number of research investigations has increased due to improved measurement techniques as well as significantly increased computer memories and performances. In this context, the present research deals with the initial stage of two-dimensional dam-break waves by comparing physical and numerical model results as well as analytical approaches. High-speed images and resulting particle image velocimetry calculations are thereby compared with the numerical volume-of-fluid (VOF) method, included in the commercial code FLOW-3D. Wave profiles and drag forces on placed obstacles are analysed in detail. Generally, a good agreement between the laboratory and VOF results is found.
KW  - VOF
KW  - PIV
KW  - physical model
KW  - numerical model
KW  - drag force
KW  - dam-break
Y1  - 2012
U6  - http://dx.doi.org/10.1080/00221686.2011.639981
SN  - 1814-2079 (E-Journal); 0022-1686 (Print)
VL  - 50
IS  - 1
SP  - 89
EP  - 97
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Bung, Daniel B.
T1  - Developing flow in skimming flow regime on embankment stepped spillways
JF  - Journal of hydraulic research
Y1  - 2011
SN  - 1814-2079 (E-Journal); 0022-1686 (Print)
VL  - Vol. 49
IS  - Iss. 5
SP  - 639
EP  - 648
PB  - Taylor & Francis
CY  - London
ER  -