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  - JOUR
A1  - Lopes, Pedro
A1  - Leandro, Jorge
A1  - Carvalho, Rita F.
A1  - Bung, Daniel B.
T1  - Alternating skimming flow over a stepped spillway
JF  - Environmental Fluid Mechanics
Y1  - 2017
U6  - http://dx.doi.org/10.1007/s10652-016-9484-x
SN  - 1573-1510
VL  - 17
IS  - 2
SP  - 303
EP  - 322
PB  - Springer
CY  - Berlin
ER  - 
TY  - CHAP
A1  - Oertel, M.
A1  - Bung, Daniel B.
ED  - Crookston, B.
ED  - Tullis, B.
T1  - Scouring processes downstream a crossbar block ramp
BT  - Session 3: Scour, erosion, sedimentation
T2  - Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016
Y1  - 2016
SN  - 978-1-884575-75-4
U6  - http://dx.doi.org/10.15142/T3340628160853
SP  - 549
EP  - 559
ER  - 
TY  - CHAP
A1  - Bung, Daniel B.
A1  - Valero, Daniel
ED  - Crookston, B.
ED  - Tullis, B.
T1  - Application of the optical flow method to velocity determination in hydraulic structure models
BT  - Session 11: Fish passage and shiplocks
T2  - Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016
Y1  - 2016
SN  - 978-1-884575-75-4
U6  - http://dx.doi.org/10.15142/T3150628160853
SP  - 223
EP  - 232
ER  - 
TY  - CHAP
A1  - Valero, Daniel
A1  - Bung, Daniel B.
A1  - Crookston, B. M.
A1  - Matos, J.
ED  - Crookston, B.
ED  - Tullis, B.
T1  - Numerical investigation of USBR type III stilling basin performance downstream of smooth and stepped spillways
BT  - Session 1: Hydraulic structures
T2  - Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016
Y1  - 2016
SN  - 978-1-884575-75-4
U6  - http://dx.doi.org/10.15142/T340628160853
SP  - 635
EP  - 646
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Bung, Daniel B.
T1  - Sensitivity of turbulent Schmidt number and turbulence model to simulations of jets in crossflow
JF  - Environmental Modelling and Software
N2  - Environmental discharges have been traditionally designed by means of cost-intensive and time-consuming experimental studies. Some extensively validated models based on an integral approach have been often employed for water quality problems, as recommended by USEPA (i.e.: CORMIX). In this study, FLOW-3D is employed for a full 3D RANS modelling of two turbulent jet-to-crossflow cases, including free surface jet impingement. Results are compared to both physical modelling and CORMIX to better assess model performance. Turbulence measurements have been collected for a better understanding of turbulent diffusion's parameter sensitivity. Although both studied models are generally able to reproduce jet trajectory, jet separation downstream of the impingement has been reproduced only by RANS modelling. Additionally, concentrations are better reproduced by FLOW-3D when the proper turbulent Schmidt number is used. This study provides a recommendation on the selection of the turbulence model and the turbulent Schmidt number for future outfall structures design studies.
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.envsoft.2016.04.030
SN  - 1364-8152 (electronic)
VL  - 82
SP  - 218
EP  - 228
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Bung, Daniel B.
T1  - Development of the interfacial air layer in the non-aerated region of high-velocity spillway flows: Instabilities growth, entrapped air and influence on the self-aeration onset
JF  - International Journal of Multiphase Flow
N2  - Self-aeration is traditionally explained by the water turbulent boundary layer outer edge intersection with the free surface. This paper presents a discussion on the commonly accepted hypothesis behind the computation of the critical point of self-aeration in spillway flows and a new formulation is proposed based on the existence of a developing air flow over the free surface. Upstream of the inception point of self-aeration, some surface roughening has been often reported in previous studies which consequently implies some entrapped air transport and air–water flows coupling. Such air flow is proven in this study by presenting measured air velocities and computing the air boundary layer thickness for a 1V:2H smooth chute flow. Additionally, the growth rate of free surface waves has been analysed by means of Ultrasonic Sensors measurements, obtaining also the entrapped air concentration. High-speed camera imaging has been used for qualitative study of the flow perturbations.
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.ijmultiphaseflow.2016.04.012
SN  - 0301-9322
VL  - 84
SP  - 66
EP  - 74
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bayon, Arnau
A1  - Valero, Daniel
A1  - Garcia-Bartual, Rafael
A1  - Vallés-Morán, Francisco José
A1  - López-Jiménez, P. Amparo
T1  - Performance assessment of OpenFOAM and FLOW-3D in the numerical modeling of a low Reynolds number hydraulic jump
JF  - Environmental Modelling & Software
N2  - A comparative performance analysis of the CFD platforms OpenFOAM and FLOW-3D is presented, focusing on a 3D swirling turbulent flow: a steady hydraulic jump at low Reynolds number. Turbulence is treated using RANS approach RNG k-ε. A Volume Of Fluid (VOF) method is used to track the air–water interface, consequently aeration is modeled using an Eulerian–Eulerian approach. Structured meshes of cubic elements are used to discretize the channel geometry. The numerical model accuracy is assessed comparing representative hydraulic jump variables (sequent depth ratio, roller length, mean velocity profiles, velocity decay or free surface profile) to experimental data. The model results are also compared to previous studies to broaden the result validation. Both codes reproduced the phenomenon under study concurring with experimental data, although special care must be taken when swirling flows occur. Both models can be used to reproduce the hydraulic performance of energy dissipation structures at low Reynolds numbers.
Y1  - 2016
SN  - 1364-8152
U6  - http://dx.doi.org/10.1016/j.envsoft.2016.02.018
VL  - 80
SP  - 322
EP  - 335
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Bung, Daniel B.
A1  - Valero, Daniel
T1  - Image processing for bubble image velocimetry in self-aerated flows
T2  - E-proceedings of the 36th IAHR World Congress 28 June – 3 July, 2015, The Hague, the Netherlands
Y1  - 2015
SP  - 1
EP  - 8
ER  - 
TY  - CHAP
A1  - Oertel, Mario
A1  - Balmes, Jan P.
A1  - Bung, Daniel B.
T1  - Numerical simulation of erosion processes on crossbar block ramps
T2  - E-proceedings of the 36th IAHR World Congress 28 June – 3 July, 2015, The Hague, the Netherlands
Y1  - 2015
SP  - 1
EP  - 8
ER  - 
TY  - CHAP
A1  - Valero, Daniel
A1  - Bung, Daniel B.
T1  - Hybrid investigation of air transport processes in moderately sloped stepped spillway flows
T2  - E-proceedings of the 36th IAHR World Congress 28 June – 3 July, 2015, The Hague, the Netherlands
Y1  - 2015
SP  - 1
EP  - 10
ER  - 
TY  - CHAP
A1  - Bung, Daniel B.
ED  - Rowinski, Pawel
T1  - Laboratory models of free-surface flows
T2  - Rivers - physical, fluvial and environmental processes
N2  - Hydraulic modeling is the classical approach to investigate and describe complex fluid motion. Many empirical formulas in the literature used for the hydraulic design of river training measures and structures have been developed using experimental data from the laboratory. Although computer capacities have increased to a high level which allows to run complex numerical simulations on standard workstation nowadays, non-standard design of structures may still raise the need to perform physical model investigations. These investigations deliver insight into details of flow patterns and the effect of varying boundary conditions. Data from hydraulic model tests may be used for calibration of numerical models as well. As the field of hydraulic modeling is very complex, this chapter intends to give a short overview on capacities and limits of hydraulic modeling in regard to river flows and hydraulic structures only. The reader shall get a first idea of modeling principles and basic considerations. More detailed information can be found in the references.
KW  - Physical modeling
KW  - Similitude
KW  - Open channels
KW  - Hydraulic structures
Y1  - 2015
SN  - 978-3-319-17718-2 ; 978-3-319-17719-9
U6  - http://dx.doi.org/10.1007/978-3-319-17719-9_9
SP  - 213
EP  - 228
PB  - Springer
CY  - Cham
ER  - 
TY  - CHAP
A1  - Chanson, Hubert
A1  - Bung, Daniel B.
A1  - Matos, J.
T1  - Stepped spillways and cascades
T2  - Energy dissipation in hydraulic structures / Hubert Chanson (ed.)
Y1  - 2015
SN  - 978-1-138-02755-8 (print) ; 978-1-315-68029-3 (e-Book)
SP  - 45
EP  - 64
PB  - CRC Press
CY  - Boca Raton, Fla. [u.a.]
ER  - 
TY  - JOUR
A1  - Oertel, Mario
A1  - Bung, Daniel B.
T1  - Stability and scour development of bed material on crossbar block ramps
JF  - International journal of sediment research
N2  - Block ramps are ecologically oriented drop structures with adequate energy dissipation and partially moderate flow velocities. A special case is given with crossbar block ramps, where the upstream and downstream level difference is reduced by a series of basins. To prevent the total structure from failing, the stability of single boulders within the crossbars and the bed material in between must be guaranteed. The present paper addresses the stability of bed material and scour development for various flow regimes. Any bed material erosion may affect the stability of the crossbar boulders, which in turn can result in major damages of the ramp. Therefore new design approaches are developed to choose an appropriate bed material size and to avoid failures of crossbar block ramp structures.
Y1  - 2015
U6  - http://dx.doi.org/10.1016/j.ijsrc.2014.12.003
SN  - 1001-6279
VL  - 30
IS  - 4
SP  - 344
EP  - 350
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Döring, Bernd
A1  - Reger, Vitali
A1  - Kuhnhenne, Markus
A1  - Feldmann, Markus
A1  - Kesti, Jyrki
A1  - Lawson, Mark
A1  - Botti, Andrea
T1  - Steel solutions for enabling zero-energy buildings
JF  - Steel Construction - Design
and Research
Y1  - 2015
U6  - http://dx.doi.org/10.1002/stco.201510029
SN  - 1867-0539
N1  - The 13th Nordic Steel Construction Conference, Tampere, 2015 (NSCC-2015)
VL  - 8
IS  - 3
SP  - 194
EP  - 200
PB  - Ernst & Sohn
CY  - Berlin
ER  - 
TY  - CHAP
A1  - Lopes, Pedro
A1  - Bung, Daniel B.
A1  - Leandro, Jorge
A1  - Carvalho, Rita F.
T1  - The effect of cross-waves in physical stepped spillway models
T2  - E-proceedings of the 36th IAHR World Congress ; 28 June - 3 July, 2015, The Hague, the Netherlands
Y1  - 2015
SP  - 1
EP  - 9
ER  - 
TY  - CHAP
A1  - Kirsch, Ansgar
T1  - Experimental and numerical investigation of the face stability of shallow tunnels in sand
T2  - Safe tunnelling for the city and environment : proceedings of the World Tunnel Congress 2009, Budapest, Hungary, 23 to 28 September 2009 / organised by International Tunnelling and Underground Space Association ...
Y1  - 2009
SP  - 1
EP  - 8
PB  - Hungarian Tunnelling Association
CY  - Budapest
ER  - 
TY  - CHAP
A1  - Fellin, Wolfgang
A1  - King, Julian
A1  - Kirsch, Ansgar
A1  - Oberguggenberger, Michael
T1  - Uncertainty modelling and sensitivity analysis of tunnel face stability
T2  - Safety, reliability and risk of structures, infrastructures and engineering systems : proceedings of the tenth International Conference on Structural Safety and Reliability (ICOSSAR 2009), Osaka, Japan, 13-17 September 2009 / ed.: Hitoshi Furuta ...
Y1  - 2009
SN  - 978-0-415-47557-0
SP  - 112
EP  - 114
PB  - CRC Pr.
CY  - Boca Raton, Fla. [u.a.]
ER  - 
TY  - CHAP
A1  - Kirsch, Ansgar
A1  - Marcher, Thomas
T1  - Numerical prediction of time-dependent rock swelling based on an example of a major tunnel project in Ontario/Canada
T2  - Numerical methods in geotechnical engineering : (NUMGE 2010) : proceedings of the seventh European Conference on Numerical Methods in Geotechnical Engineering, Trondheim, Norway, 2 - 4 June 2010 / ed. by Thomas Benz ...
Y1  - 2010
SN  - 978-0-415-59239-0
SP  - 297
EP  - 302
PB  - Taylor and Francis
CY  - London
ER  - 
TY  - CHAP
A1  - Kirsch, Ansgar
T1  - Numerical investigation of the face stability of shallow tunnels in sand
T2  - Numerical methods in geotechnical engineering : (NUMGE 2010) : proceedings of the seventh European Conference on Numerical Methods in Geotechnical Engineering, Trondheim, Norway, 2 - 4 June 2010 / ed. by Thomas Benz ...
Y1  - 2010
SN  - 978-0-415-59239-0
SP  - 779
EP  - 784
PB  - Taylor and Francis
CY  - London
ER  -