@article{BungValero2018,
  author    = {Bung, Daniel B. and Valero, Daniel},
  title     = {Re-aeration on stepped spillways with special consideration of entrained and entrapped air},
  series = {Geosciences},
  volume    = {8},
  journal   = {Geosciences},
  number    = {9},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2076-3263},
  pages     = {Article number 333},
  year      = {2018},
  abstract  = {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.},
  language  = {en}
}
@inproceedings{BungPagliara2013,
  author    = {Bung, Daniel B. and Pagliara, S.},
  title     = {Proceedings of the International Workshop on Hydraulic Design of Low-Head Structures : Aachen, Germany, February, 20-22, 2013 / D. Bung ; S. Pagliara (eds.)},
  publisher = {Bundesanst. f{\"u}r Wasserbau},
  address   = {Karlsruhe},
  isbn      = {978-3-939230-04-5},
  pages     = {X, 230 S. + 1 CD-ROM},
  year      = {2013},
  language  = {en}
}
@inproceedings{SchlenkhoffBung2009,
  author    = {Schlenkhoff, Andreas and Bung, Daniel B.},
  title     = {Prediction of oxygen transfer in self-aerated skimming flow on embankment stepped spillways},
  series = {Water engineering for sustainable environment : 33rd IAHR congress ; 9 - 14 August 2009, Vancouver, British Columbia, Canada},
  booktitle = {Water engineering for sustainable environment : 33rd IAHR congress ; 9 - 14 August 2009, Vancouver, British Columbia, Canada},
  organization    = {International Association for Hydraulic Engineering and Research},
  isbn      = {9789078046080},
  pages     = {1 CD-ROM},
  year      = {2009},
  language  = {en}
}
@inproceedings{KerpenBungSchlurmann2010,
  author    = {Kerpen, N. B. and Bung, Daniel B. and Schlurmann, Torsten},
  title     = {Physical model investigations of ships passing through a lock},
  series = {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},
  booktitle = {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},
  editor    = {Janssen, Robert},
  publisher = {School of Civil Engineeering, The University of Queensland},
  address   = {Brisbane},
  organization    = {International Junior Researcher and Engineer Workshop on Hydraulic Structures <3, 2010, Edinburgh>},
  isbn      = {9781742720159},
  pages     = {93 -- 100},
  year      = {2010},
  language  = {en}
}
@inproceedings{KerpenBungSchlurmann2010,
  author    = {Kerpen, N. B. and Bung, Daniel B. and Schlurmann, Torsten},
  title     = {Physical model investigations of pressure distributions next to ships passing through a lock},
  series = {5th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : CG JOINT 2010},
  booktitle = {5th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : CG JOINT 2010},
  publisher = {Univ. Press},
  address   = {Tianjin},
  organization    = {Chinese-German Joint Symposium on Hydraulic and Ocean Engineering <5, 2010, Tianjin>},
  isbn      = {978-7-5618-3671-2},
  pages     = {514 -- 519},
  year      = {2010},
  language  = {en}
}
@article{ValeroSchalkoFriedrichetal.2021,
  author    = {Valero, Daniel and Schalko, Isabella and Friedrich, Heide and Abad, Jorge D. and Bung, Daniel B. and Donchyts, Gennadii and Felder, Stefan and Ferreira, Rui M. L. and Hohermuth, Benjamin and Kramer, Matthias and Li, Danxun and Mendes, Luis and Moreno-Rodenas, Antonio and Nones, Michael and Paron, Paolo and Ruiz-Villanueva, Virginia and Wang, Ruo-Qian and Franca, Mario J.},
  title     = {Pathways towards democratization of hydro-environment observations and data},
  series = {Iahr White Paper Series},
  journal   = {Iahr White Paper Series},
  number    = {1},
  publisher = {International Association for Hydro-Environment Engineering and Research (IAHR)},
  pages     = {1 -- 9},
  year      = {2021},
  language  = {en}
}
@inproceedings{BungSchlenkhoff2008,
  author    = {Bung, Daniel B. and Schlenkhoff, Andreas},
  title     = {Optimization of the reaeration potential on embankment stepped spillways in skimming flow regime},
  series = {Hydraulic structures : proceedings of the second International Junior Researcher and Engineer Workshop on Hydraulic Structures, Pisa, Italy, 30 July-1 August 2008},
  booktitle = {Hydraulic structures : proceedings of the second International Junior Researcher and Engineer Workshop on Hydraulic Structures, Pisa, Italy, 30 July-1 August 2008},
  editor    = {Pagliara, Stefano},
  organization    = {International Junior Researcher and Engineer Workshop on Hydraulic Structures <2, 2008, Pisa>},
  isbn      = {978-88-8492-568-8},
  pages     = {97 -- 106},
  year      = {2008},
  language  = {en}
}
@article{BungValero2016,
  author    = {Bung, Daniel B. and Valero, Daniel},
  title     = {Optical flow estimation in aerated flows},
  series = {Journal of Hydraulic Research},
  volume    = {54},
  journal   = {Journal of Hydraulic Research},
  number    = {5},
  publisher = {Taylor \& Francis},
  address   = {London},
  doi       = {10.1080/00221686.2016.1173600},
  pages     = {575 -- 580},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{ZhangValeroBungetal.2018,
  author    = {Zhang, G. and Valero, Daniel and Bung, Daniel B. and Chanson, H.},
  title     = {On the estimation of free-surface turbulence using ultrasonic sensors},
  series = {Flow Measurement and Instrumentation},
  volume    = {60},
  journal   = {Flow Measurement and Instrumentation},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0955-5986},
  doi       = {10.1016/j.flowmeasinst.2018.02.009},
  pages     = {171 -- 184},
  year      = {2018},
  abstract  = {Accurate determination of free-surface dynamics has attracted much research attention during the past decade and has important applications in many environmental and water related areas. In this study, the free-surface dynamics in several turbulent flows commonly found in nature were investigated using a synchronised setup consisting of an ultrasonic sensor and a high-speed video camera. Basic sensor capabilities were examined in dry conditions to allow for a better characterisation of the present sensor model. The ultrasonic sensor was found to adequately reproduce free-surface dynamics up to the second order, especially in two-dimensional scenarios with the most energetic modes in the low frequency range. The sensor frequency response was satisfactory in the sub-20 Hz band, and its signal quality may be further improved by low-pass filtering prior to digitisation. The application of the USS to characterise entrapped air in high-velocity flows is also discussed.},
  language  = {en}
}
@inproceedings{ValeroBungErpicumetal.2017,
  author    = {Valero, Daniel and Bung, Daniel B. and Erpicum, Sebastien and Dewals, Benjamin},
  title     = {Numerical study of turbulent oscillations around a cylinder: RANS capabilities and sensitivity analysis},
  series = {Proceedings of the 37th IAHR World Congress August 13 - 18, 2017, Kuala Lumpur, Malaysia},
  booktitle = {Proceedings of the 37th IAHR World Congress August 13 - 18, 2017, Kuala Lumpur, Malaysia},
  issn      = {2521-716X},
  pages     = {3126 -- 3135},
  year      = {2017},
  language  = {en}
}