@article{Hoettges1992,
  author    = {H{\"o}ttges, J{\"o}rg},
  title     = {A Full Finite Element Solution for the Unsteady Advection-Diffusion Equation},
  series = {Computational methods in water resources : [proceedings of the Ninth International Conference on Computational Methods in Water Resources held at the University of Colorado at Denver, U.S.A., in June 1992] / ed.: T. F. Russell},
  journal   = {Computational methods in water resources : [proceedings of the Ninth International Conference on Computational Methods in Water Resources held at the University of Colorado at Denver, U.S.A., in June 1992] / ed.: T. F. Russell},
  publisher = {Computational Mechanics Publications [u.a.]},
  address   = {Southampton [u.a.]},
  isbn      = {185312169X},
  year      = {1992},
  language  = {en}
}
@article{Jochim2004,
  author    = {Jochim, Haldor E.},
  title     = {A traffic resistance model of long-distance travel},
  series = {Networks for mobility : 2nd international symposium, September 29 - October 1, 2004, Stuttgart, Germany ; proceedings ; abstracts and CD-ROM / [2nd International Symposium on Networks for Mobility]. FOVUS, Centre of Transportation Research, University of},
  journal   = {Networks for mobility : 2nd international symposium, September 29 - October 1, 2004, Stuttgart, Germany ; proceedings ; abstracts and CD-ROM / [2nd International Symposium on Networks for Mobility]. FOVUS, Centre of Transportation Research, University of},
  publisher = {FOVUS},
  address   = {Stuttgart},
  isbn      = {3-89301-180-3},
  pages     = {X, 84 S. : graph. Darst. + 1 CD-ROM},
  year      = {2004},
  language  = {en}
}
@article{BungErpicumTullis2020,
  author    = {Bung, Daniel Bernhard and Erpicum, S{\´e}bastien and Tullis, Blanke P.},
  title     = {Advances in hydraulic structures engineering},
  series = {Journal of Hydraulic Engineering},
  volume    = {147},
  journal   = {Journal of Hydraulic Engineering},
  number    = {1},
  publisher = {ASCE},
  address   = {Reston, Va.},
  issn      = {0733-9429 (Druckausgabe)},
  doi       = {10.1061/(ASCE)HY.1943-7900.0001851},
  pages     = {1 Seite},
  year      = {2020},
  language  = {en}
}
@article{LopesLeandroCarvalhoetal.2017,
  author    = {Lopes, Pedro and Leandro, Jorge and Carvalho, Rita F. and Bung, Daniel B.},
  title     = {Alternating skimming flow over a stepped spillway},
  series = {Environmental Fluid Mechanics},
  volume    = {17},
  journal   = {Environmental Fluid Mechanics},
  number    = {2},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1573-1510},
  doi       = {10.1007/s10652-016-9484-x},
  pages     = {303 -- 322},
  year      = {2017},
  language  = {en}
}
@article{BienerBethkeSasseetal.2003,
  author    = {Biener, Ernst and Bethke, H. and Sasse, T. and Wernhoff, T.},
  title     = {Alternative landfill capping using locally available recycled material},
  series = {Land contamination \& reclamation. 14 (2003), H. 4},
  journal   = {Land contamination \& reclamation. 14 (2003), H. 4},
  isbn      = {0967-0513},
  pages     = {419 -- 427},
  year      = {2003},
  language  = {en}
}
@article{CheenakulaHoffstadtKrafftetal.2022,
  author    = {Cheenakula, Dheeraja and Hoffstadt, Kevin and Krafft, Simone and Reinecke, Diana and Klose, Holger and Kuperjans, Isabel and Gr{\"o}mping, Markus},
  title     = {Anaerobic digestion of algal-bacterial biomass of an Algal Turf Scrubber system},
  series = {Biomass Conversion and Biorefinery},
  volume    = {13},
  journal   = {Biomass Conversion and Biorefinery},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2190-6823},
  doi       = {10.1007/s13399-022-03236-z},
  pages     = {15 Seiten},
  year      = {2022},
  abstract  = {This study investigated the anaerobic digestion of an algal-bacterial biofilm grown in artificial wastewater in an Algal Turf Scrubber (ATS). The ATS system was located in a greenhouse (50°54′19ʺN, 6°24′55ʺE, Germany) and was exposed to seasonal conditions during the experiment period. The methane (CH4) potential of untreated algal-bacterial biofilm (UAB) and thermally pretreated biofilm (PAB) using different microbial inocula was determined by anaerobic batch fermentation. Methane productivity of UAB differed significantly between microbial inocula of digested wastepaper, a mixture of manure and maize silage, anaerobic sewage sludge, and percolated green waste. UAB using sewage sludge as inoculum showed the highest methane productivity. The share of methane in biogas was dependent on inoculum. Using PAB, a strong positive impact on methane productivity was identified for the digested wastepaper (116.4\%) and a mixture of manure and maize silage (107.4\%) inocula. By contrast, the methane yield was significantly reduced for the digested anaerobic sewage sludge (50.6\%) and percolated green waste (43.5\%) inocula. To further evaluate the potential of algal-bacterial biofilm for biogas production in wastewater treatment and biogas plants in a circular bioeconomy, scale-up calculations were conducted. It was found that a 0.116 km2 ATS would be required in an average municipal wastewater treatment plant which can be viewed as problematic in terms of space consumption. However, a substantial amount of energy surplus (4.7-12.5 MWh a-1) can be gained through the addition of algal-bacterial biomass to the anaerobic digester of a municipal wastewater treatment plant. Wastewater treatment and subsequent energy production through algae show dominancy over conventional technologies.},
  language  = {en}
}
@article{ValeroBung2017,
  author    = {Valero, Daniel and Bung, Daniel B.},
  title     = {Artificial Neural Networks and pattern recognition for air-water flow velocity estimation using a single-tip optical fibre probe},
  series = {Journal of Hydro-environment Research},
  volume    = {19},
  journal   = {Journal of Hydro-environment Research},
  number    = {3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1570-6443},
  doi       = {10.1016/j.jher.2017.08.004},
  pages     = {150 -- 159},
  year      = {2017},
  language  = {en}
}
@article{BienerRouve1984,
  author    = {Biener, Ernst and Rouv{\´e}, G.},
  title     = {Behaviour and maintenance of some old masonry gravity dams},
  series = {Safety of dams : proceedings of the International Conference on Safety of Dams, Coimbra, 23-28 April 1984 / ed. by J. Laginha Serafim. - [Hauptbd.]},
  journal   = {Safety of dams : proceedings of the International Conference on Safety of Dams, Coimbra, 23-28 April 1984 / ed. by J. Laginha Serafim. - [Hauptbd.]},
  publisher = {Rotterdam [u.a.]},
  address   = {Balkema},
  isbn      = {90-6191-522-8},
  pages     = {101 -- 106},
  year      = {1984},
  language  = {en}
}
@article{Jochim2002,
  author    = {Jochim, Haldor E.},
  title     = {Charging rail operators for delays - how not to do it},
  series = {Networks for mobility : International Symposium, September 18 - 20, 2002, Stuttgart, Germany ; proceedings / University of Stuttgart, Centre of Transporation Research (FOVUS). W. M{\"o}hlenbrink ... (eds.)},
  journal   = {Networks for mobility : International Symposium, September 18 - 20, 2002, Stuttgart, Germany ; proceedings / University of Stuttgart, Centre of Transporation Research (FOVUS). W. M{\"o}hlenbrink ... (eds.)},
  publisher = {FOVUS},
  address   = {Stuttgart},
  isbn      = {3893010858},
  year      = {2002},
  language  = {en}
}
@article{ValeroBungCrookston2019,
  author    = {Valero, D. and Bung, Daniel B. and Crookston, B. M.},
  title     = {Closure to "Energy Dissipation of a Type III Basin under Design and Adverse Conditions for Stepped and Smooth Spillways"},
  series = {Journal of Hydraulic Engineering},
  volume    = {146},
  journal   = {Journal of Hydraulic Engineering},
  number    = {2},
  publisher = {ASCE},
  address   = {Reston, Va.},
  doi       = {10.1061/(ASCE)HY.1943-7900.0001669},
  year      = {2019},
  language  = {en}
}
@article{HoettgesArnoldRouve1989,
  author    = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard},
  title     = {Combined Digital Image and Finite Element Analysis of Mixing in Compound Open Channel Flow / Arnold, U.; J. H{\"o}ttges; G. Rouv{\´e}},
  series = {Refined flow modelling and turbulence measurements : proceedings of the Third International Symposium Tokyo, Japan 26 - 28 July, 1988 / ed. by Y. Iwasa. Scientific Organizing Committee of the Third International Symposium on Refined Flow Modelling and Tur},
  journal   = {Refined flow modelling and turbulence measurements : proceedings of the Third International Symposium Tokyo, Japan 26 - 28 July, 1988 / ed. by Y. Iwasa. Scientific Organizing Committee of the Third International Symposium on Refined Flow Modelling and Tur},
  publisher = {Universal Acad. Press},
  address   = {Tokyo},
  isbn      = {4-946443-03-7},
  pages     = {569 -- 576},
  year      = {1989},
  language  = {en}
}
@article{CheenakulaGriebelMontagetal.2023,
  author    = {Cheenakula, Dheeraja and Griebel, Kai and Montag, David and Gr{\"o}mping, Markus},
  title     = {Concept development of a mainstream deammonification and comparison with conventional process in terms of energy, performance and economical construction perspectives},
  series = {Frontiers in Microbiology},
  volume    = {14},
  journal   = {Frontiers in Microbiology},
  number    = {11155235},
  editor    = {Huang, Xiaowu},
  publisher = {Frontiers},
  issn      = {1664-302X},
  doi       = {10.3389/fmicb.2023.1155235},
  pages     = {1 -- 15},
  year      = {2023},
  abstract  = {Deammonification for nitrogen removal in municipal wastewater in temperate and cold climate zones is currently limited to the side stream of municipal wastewater treatment plants (MWWTP). This study developed a conceptual model of a mainstream deammonification plant, designed for 30,000 P.E., considering possible solutions corresponding to the challenging mainstream conditions in Germany. In addition, the energy-saving potential, nitrogen elimination performance and construction-related costs of mainstream deammonification were compared to a conventional plant model, having a single-stage activated sludge process with upstream denitrification. The results revealed that an additional treatment step by combining chemical precipitation and ultra-fine screening is advantageous prior the mainstream deammonification. Hereby chemical oxygen demand (COD) can be reduced by 80\% so that the COD:N ratio can be reduced from 12 to 2.5. Laboratory experiments testing mainstream conditions of temperature (8-20°C), pH (6-9) and COD:N ratio (1-6) showed an achievable volumetric nitrogen removal rate (VNRR) of at least 50 gN/(m3∙d) for various deammonifying sludges from side stream deammonification systems in the state of North Rhine-Westphalia, Germany, where m3 denotes reactor volume. Assuming a retained Norganic content of 0.0035 kgNorg./(P.E.∙d) from the daily loads of N at carbon removal stage and a VNRR of 50 gN/(m3∙d) under mainstream conditions, a resident-specific reactor volume of 0.115 m3/(P.E.) is required for mainstream deammonification. This is in the same order of magnitude as the conventional activated sludge process, i.e., 0.173 m3/(P.E.) for an MWWTP of size class of 4. The conventional plant model yielded a total specific electricity demand of 35 kWh/(P.E.∙a) for the operation of the whole MWWTP and an energy recovery potential of 15.8 kWh/(P.E.∙a) through anaerobic digestion. In contrast, the developed mainstream deammonification model plant would require only a 21.5 kWh/(P.E.∙a) energy demand and result in 24 kWh/(P.E.∙a) energy recovery potential, enabling the mainstream deammonification model plant to be self-sufficient. The retrofitting costs for the implementation of mainstream deammonification in existing conventional MWWTPs are nearly negligible as the existing units like activated sludge reactors, aerators and monitoring technology are reusable. However, the mainstream deammonification must meet the performance requirement of VNRR of about 50 gN/(m3∙d) in this case.},
  language  = {en}
}
@article{BienerSasse1993,
  author    = {Biener, Ernst and Sasse, T.},
  title     = {Construction and rehabilitation of landfill shafts},
  series = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1},
  journal   = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1},
  publisher = {CISA, Environmental Sanitary Engineering Centre},
  address   = {Cagliari},
  pages     = {451 -- 460},
  year      = {1993},
  language  = {en}
}
@article{BienerSasse1994,
  author    = {Biener, Ernst and Sasse, T.},
  title     = {Construction of composite lining systems under unfavourable weather conditions},
  series = {Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl.},
  journal   = {Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl.},
  publisher = {Spon},
  address   = {London [u.a.]},
  isbn      = {0419159908},
  pages     = {183 -- 200},
  year      = {1994},
  language  = {en}
}
@article{WoliszSchuetzBlankeetal.2017,
  author    = {Wolisz, Henryk and Sch{\"u}tz, Thomas and Blanke, Tobias and Hagenkamp, Markus and Kohrn, Markus and Wesseling, Mark and M{\"u}ller, Dirk},
  title     = {Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets},
  series = {Energy},
  volume    = {137},
  journal   = {Energy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.energy.2017.06.025},
  pages     = {715 -- 728},
  year      = {2017},
  language  = {en}
}
@article{Bung2011,
  author    = {Bung, Daniel B.},
  title     = {Developing flow in skimming flow regime on embankment stepped spillways},
  series = {Journal of hydraulic research},
  volume    = {Vol. 49},
  journal   = {Journal of hydraulic research},
  number    = {Iss. 5},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {1814-2079 (E-Journal); 0022-1686 (Print)},
  pages     = {639 -- 648},
  year      = {2011},
  language  = {en}
}
@article{ValeroBung2016,
  author    = {Valero, Daniel and Bung, Daniel B.},
  title     = {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},
  series = {International Journal of Multiphase Flow},
  volume    = {84},
  journal   = {International Journal of Multiphase Flow},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9322},
  doi       = {10.1016/j.ijmultiphaseflow.2016.04.012},
  pages     = {66 -- 74},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{ValeroBungCrookston2018,
  author    = {Valero, Daniel and Bung, Daniel B. and Crookston, B.M.},
  title     = {Energy dissipation of a Type III basin under design and adverse conditions for stepped and smooth spillways},
  series = {Journal of Hydraulic Engineering},
  volume    = {144},
  journal   = {Journal of Hydraulic Engineering},
  number    = {7},
  publisher = {ASCE},
  address   = {Reston, Va.},
  issn      = {0733-9429},
  doi       = {10.1061/(ASCE)HY.1943-7900.0001482},
  year      = {2018},
  abstract  = {New information regarding the influence of a stepped chute on the hydraulic performance of the United States Bureau of Reclamation (Reclamation) Type III hydraulic jump stilling basin is presented for design (steady) and adverse (decreasing tailwater) conditions. Using published experimental data and computational fluid dynamics (CFD) models, this paper presents a detailed comparison between smooth-chute and stepped-chute configurations for chute slopes of 0.8H:1V and 4H:1V and Froude numbers (F) ranging from 3.1 to 9.5 for a Type III basin designed for F = 8. For both stepped and smooth chutes, the relative role of each basin element was quantified, up to the most hydraulic extreme case of jump sweep-out. It was found that, relative to a smooth chute, the turbulence generated by a stepped chute causes a higher maximum velocity decay within the stilling basin, which represents an enhancement of the Type III basin's performance but also a change in the relative role of the basin elements. Results provide insight into the ability of the CFD models [unsteady Reynolds-averaged Navier-Stokes (RANS) equations with renormalization group (RNG) k-ϵ turbulence model and volume-of-fluid (VOF) for free surface tracking] to predict the transient basin flow structure and velocity profiles. Type III basins can perform adequately with a stepped chute despite the effects steps have on the relative role of each basin element. It is concluded that the classic Type III basin design, based upon methodology by reclamation specific to smooth chutes, can be hydraulically improved for the case of stepped chutes for design and adverse flow conditions using the information presented herein.},
  language  = {en}
}
@article{KerpenBungValeroetal.2017,
  author    = {Kerpen, Nils B. and Bung, Daniel B. and Valero, Daniel and Schlurmann, Torsten},
  title     = {Energy dissipation within the wave run-up at stepped revetments},
  series = {Journal of Ocean University of China},
  volume    = {16},
  journal   = {Journal of Ocean University of China},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1993-5021},
  doi       = {10.1007/s11802-017-3355-z},
  pages     = {649 -- 654},
  year      = {2017},
  language  = {en}
}
@article{BienerSasse1988,
  author    = {Biener, Ernst and Sasse, T.},
  title     = {Experience with new techniques in slurry cutoff wall construction},
  series = {ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations},
  journal   = {ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations},
  publisher = {Acad. Press},
  address   = {London [u.a.]},
  isbn      = {0-12-058451-4},
  pages     = {41 -- 46},
  year      = {1988},
  language  = {en}
}
@article{Kirsch2010,
  author    = {Kirsch, Ansgar},
  title     = {Experimental investigation of the face stability of shallow tunnels in sand},
  series = {Acta Geotechnica},
  volume    = {5},
  journal   = {Acta Geotechnica},
  number    = {1},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1861-1125},
  doi       = {10.1007/s11440-010-0110-7},
  pages     = {43 -- 62},
  year      = {2010},
  abstract  = {Various models have been proposed for the prediction of the necessary support pressure at the face of a shallow tunnel. To assess their quality, the collapse of a tunnel face was modelled with small-scale model tests at single gravity. The development of the failure mechanism and the support force at the face in dry sand were investigated. The observed displacement patterns show a negligible influence of overburden on the extent and evolution of the failure zone. The latter is significantly influenced, though, by the initial density of the sand: in dense sand a chimney-wedge-type collapse mechanism developed, which propagated towards the soil surface. Initially, loose sand did not show any discrete collapse mechanism. The necessary support force was neither influenced by the overburden nor the initial density. A comparison with quantitative predictions by several theoretical models showed that the measured necessary support pressure is overestimated by most of the models. Those by Vermeer/Ruse and L{\´e}ca/Dormieux showed the best agreement to the measurements.},
  language  = {en}
}
@article{HoettgesFeldhausBrockhausetal.1992,
  author    = {H{\"o}ttges, J{\"o}rg and Feldhaus, R. and Brockhaus, T. and Rouv{\´e}, Gerhard},
  title     = {Finite Element Simulation of Flow and Pollution Transport applied to a Part of the River Rhine / Feldhaus, R.; J. H{\"o}ttges, T. Brockhaus; G. Rouv{\´e}},
  series = {Hydraulic and environmental modelling : proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters / [IAHR-AIRH]. Ed. by R. A. Falconer},
  journal   = {Hydraulic and environmental modelling : proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters / [IAHR-AIRH]. Ed. by R. A. Falconer},
  publisher = {Ashgate},
  address   = {Aldershot, Hants, UK [u.a.]},
  year      = {1992},
  language  = {en}
}
@article{KerresGredigkHoffmannJatheetal.2020,
  author    = {Kerres, Karsten and Gredigk-Hoffmann, Sylvia and Jathe, R{\"u}diger and Orlik, Stefan and Sariyildiz, Mustafa and Schmidt, Torsten and Sympher, Klaus-Jochen and Uhlenbroch, Adrian},
  title     = {Future approaches for sewer system condition assessment},
  series = {Water Practice \& Technology},
  journal   = {Water Practice \& Technology},
  number    = {15 (2)},
  publisher = {IWA Publishing},
  address   = {London},
  issn      = {1751-231X},
  doi       = {10.2166/wpt.2020.027},
  pages     = {386 -- 393},
  year      = {2020},
  abstract  = {Different analytical approaches exist to describe the structural substance or wear reserve of sewer systems. The aim is to convert engineering assessments of often complex defect patterns into computational algorithms and determine a substance class for a sewer section or manhole. This analytically determined information is essential for strategic rehabilitation planning processes up to network level, as it corresponds to the most appropriate rehabilitation type and can thus provide decision-making support. Current calculation methods differ clearly from each other in parts, so that substance classes determined by the different approaches are only partially comparable with each other. The objective of the German R\&D cooperation project 'SubKanS' is to develop a methodology for classifying the specific defect patterns resulting from the interaction of all the individual defects, and their severities and locations. The methodology takes into account the structural substance of sewer sections and manholes, based on real data and theoretical considerations analogous to the condition classification of individual defects. The result is a catalogue of defect patterns and characteristics, as well as associated structural substance classifications of sewer systems (substance classes). The methodology for sewer system substance classification is developed so that the classification of individual defects can be transferred into a substance class of the sewer section or manhole, eventually taking into account further information (e.g. pipe material, nominal diameter, etc.). The result is a validated methodology for automated sewer system substance classification.},
  language  = {en}
}
@article{BienerBoykenSasseetal.1999,
  author    = {Biener, Ernst and Boyken, P. and Sasse, T. and Arnold, J.},
  title     = {Geotechnical aspects of the construction of the integrated harbour sludge management system in Bremen-Seehausen / P. Boyken ; E. Biener ; T. Sasse ; J. Arnold},
  series = {Geotechnical engineering for transportation infrastructure : proceedings of the twelfth European Conference on Soil Mechanics and Geotechnical Engineering, Amsterdam, Netherlands, 7 - 10 June 1999 ; theory and practice, planning and design, construction and maintenance. - Vol. 2},
  journal   = {Geotechnical engineering for transportation infrastructure : proceedings of the twelfth European Conference on Soil Mechanics and Geotechnical Engineering, Amsterdam, Netherlands, 7 - 10 June 1999 ; theory and practice, planning and design, construction and maintenance. - Vol. 2},
  publisher = {Balkema},
  address   = {Rotterdam},
  isbn      = {90-5809-049-3},
  pages     = {909 -- 914},
  year      = {1999},
  language  = {en}
}
@article{ErpicumCrookstonBombardellietal.2021,
  author    = {Erpicum, Sebastien and Crookston, Brian M. and Bombardelli, Fabian and Bung, Daniel B. and Felder, Stefan and Mulligan, Sean and Oertel, Mario and Palermo, Michele},
  title     = {Hydraulic structures engineering: An evolving science in a changing world},
  series = {Wires Water},
  volume    = {8},
  journal   = {Wires Water},
  number    = {2},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {2049-1948},
  doi       = {10.1002/wat2.1505},
  year      = {2021},
  language  = {en}
}
@article{KuhnhenneRegerPyschnyetal.2020,
  author    = {Kuhnhenne, Markus and Reger, Vitali and Pyschny, Dominik and D{\"o}ring, Bernd},
  title     = {Influence of airtightness of steel sandwich panel joints on heat losses},
  series = {E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020)},
  volume    = {172},
  journal   = {E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020)},
  number    = {Art. 05008},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  doi       = {10.1051/e3sconf/202017205008},
  pages     = {6},
  year      = {2020},
  abstract  = {Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency.},
  language  = {en}
}
@article{OertelBung2012,
  author    = {Oertel, Mario and Bung, Daniel B.},
  title     = {Initial stage of two-dimensional dam-break waves: laboratory versus VOF},
  series = {Journal of hydraulic research},
  volume    = {50},
  journal   = {Journal of hydraulic research},
  number    = {1},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {1814-2079 (E-Journal); 0022-1686 (Print)},
  doi       = {10.1080/00221686.2011.639981},
  pages     = {89 -- 97},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{BienerBoykenSasse1997,
  author    = {Biener, Ernst and Boyken, P. and Sasse, T.},
  title     = {Integrated dredged material management system of Bremen-Seehausen},
  series = {Sardinia 97 : proceedings ; [13 - 17 October 1997, S. Margherita di Pula - Cagliari, Sardinia, Italy] / Sixth International Landfill Symposium. Ed.: Thomas H. Christensen... - Bd. 5 : Landfill regulations, waste characteristics, landfilling in middle and lower income countries, industrial wastes and monolandfills},
  journal   = {Sardinia 97 : proceedings ; [13 - 17 October 1997, S. Margherita di Pula - Cagliari, Sardinia, Italy] / Sixth International Landfill Symposium. Ed.: Thomas H. Christensen... - Bd. 5 : Landfill regulations, waste characteristics, landfilling in middle and lower income countries, industrial wastes and monolandfills},
  publisher = {CISA, Environmental Sanitary Engineering Centre},
  address   = {Cagliari},
  pages     = {497 -- 502},
  year      = {1997},
  language  = {en}
}
@article{HoettgesArnoldRouve1994,
  author    = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard},
  title     = {Measurement of transverse mixing using digital image acquisition},
  series = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven},
  journal   = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven},
  publisher = {Wiley},
  address   = {Chichester [u.a.]},
  isbn      = {0471941425},
  pages     = {XVI, 458 S., [8] Bl : Ill. (z.T. farb.), graph. Da},
  year      = {1994},
  language  = {en}
}
@article{LeandroBungCarvalho2014,
  author    = {Leandro, J. and Bung, Daniel B. and Carvalho, R.},
  title     = {Measuring void fraction and velocity fields of a stepped spillway for skimming flow using non-intrusive methods},
  series = {Experiments in fluids},
  journal   = {Experiments in fluids},
  number    = {55},
  publisher = {Springer Nature},
  address   = {Heidelberg},
  issn      = {0723-4864 (Print) ; 1432-1114 (Online)},
  doi       = {10.1007/s00348-014-1732-6},
  pages     = {Art. 1732},
  year      = {2014},
  language  = {en}
}
@article{BlankeHagenkampDoeringetal.2021,
  author    = {Blanke, Tobias and Hagenkamp, Markus and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Reger, Vitali and Kuhnhenne, Markus},
  title     = {Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates},
  series = {Geothermal Energy},
  volume    = {9},
  journal   = {Geothermal Energy},
  number    = {Article number: 19},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2195-9706},
  doi       = {10.1186/s40517-021-00201-3},
  pages     = {23 Seiten},
  year      = {2021},
  abstract  = {Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellstr{\"o}m's borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54\% of the outer pipe radius for laminar fow and 60\% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth's thermal properties and the fow type. Conclusively, coaxial geothermal probes' design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.},
  language  = {en}
}
@article{BienerSasseArnoldetal.1999,
  author    = {Biener, Ernst and Sasse, T. and Arnold, J. and Woltering, S.},
  title     = {New treatment of harbour sludge in Bremen and Bremerhaven / E. Biener ; T. Sasse ; J. Arnold ; S. Woltering ; N. Binder},
  series = {Characterisation and treatment of sediments : Antwerpen, Belgium, September 15 - 17, 1999 ; [preceded by 12th International Harbour Congress] ; proceedings / CATS 4. Ed.: G. De Schutter. Organized by: Technologisch Instituut, Koninklijke Vlaamse Ingenieursvereniging},
  journal   = {Characterisation and treatment of sediments : Antwerpen, Belgium, September 15 - 17, 1999 ; [preceded by 12th International Harbour Congress] ; proceedings / CATS 4. Ed.: G. De Schutter. Organized by: Technologisch Instituut, Koninklijke Vlaamse Ingenieursvereniging},
  publisher = {Technolog. Inst.},
  address   = {Anvers},
  isbn      = {9076019118},
  pages     = {115 -- 122},
  year      = {1999},
  language  = {en}
}
@article{Bung2013,
  author    = {Bung, Daniel B.},
  title     = {Non-intrusive detection of air-water surface roughness in self-aerated chute flows},
  series = {Journal of hydraulic research},
  volume    = {Vol. 51},
  journal   = {Journal of hydraulic research},
  number    = {Iss. 3},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {1814-2079 (E-Journal); 0022-1686 (Print)},
  pages     = {322 -- 329},
  year      = {2013},
  language  = {en}
}
@article{ValeroVitiGualtieri2019,
  author    = {Valero, Daniel and Viti, Nicolo and Gualtieri, Carlo},
  title     = {Numerical Simulation of Hydraulic Jumps. Part 1: Experimental Data for Modelling Performance Assessment},
  series = {Water},
  volume    = {11},
  journal   = {Water},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4441},
  doi       = {10.3390/w11010036},
  pages     = {Art. Nr. 36},
  year      = {2019},
  language  = {en}
}
@article{VitiValeroGualtieri2019,
  author    = {Viti, Nicolo and Valero, Daniel and Gualtieri, Carlo},
  title     = {Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook},
  series = {Water},
  volume    = {11},
  journal   = {Water},
  number    = {1},
  issn      = {2073-4441},
  doi       = {10.3390/w11010028},
  pages     = {Art. Nr. 28},
  year      = {2019},
  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}
}
@article{CheenakulaPaulsenOttetal.2023,
  author    = {Cheenakula, Dheeraja and Paulsen, Svea and Ott, Fabian and Gr{\"o}mping, Markus},
  title     = {Operational window of a deammonifying sludge for mainstream application in a municipal wastewater treatment plant},
  series = {Water and Environment Journal},
  journal   = {Water and Environment Journal},
  number    = {Early View},
  publisher = {Wiley},
  address   = {Chichester},
  issn      = {1747-6593},
  doi       = {10.1111/wej.12898},
  pages     = {1 -- 12},
  year      = {2023},
  abstract  = {The present work aimed to study the mainstream feasibility of the deammonifying sludge of side stream of municipal wastewater treatment plant (MWWTP) in Kaster, Germany. For this purpose, the deammonifying sludge available at the side stream was investigated for nitrogen (N) removal with respect to the operational factors temperature (15-30°C), pH value (6.0-8.0) and chemical oxygen demand (COD)/N ratio (≤1.5-6.0). The highest and lowest N-removal rates of 0.13 and 0.045 kg/(m³ d) are achieved at 30 and 15°C, respectively. Different conditions of pH and COD/N ratios in the SBRs of Partial nitritation/anammox (PN/A) significantly influenced both the metabolic processes and associated N-removal rates. The scientific insights gained from the current work signifies the possibility of mainstream PN/A at WWTPs. The current study forms a solid basis of operational window for the upcoming semi-technical trails to be conducted prior to the full-scale mainstream PN/A at WWTP Kaster and WWTPs globally.},
  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{HoettgesRitterbachEls1987,
  author    = {H{\"o}ttges, J{\"o}rg and Ritterbach, E. and Els, H.},
  title     = {Optical Improvement of LDV-Measurement in Pipe Flow / Ritterbach, E.; J. H{\"o}ttges; H. Els},
  series = {Laser anemometry : advances and applications; proceedings of the 2. International Conference, Strathclyde, Scotland, 21st to 23rd September 1987 / ed. by John Turner ... UK LDA Users Group},
  journal   = {Laser anemometry : advances and applications; proceedings of the 2. International Conference, Strathclyde, Scotland, 21st to 23rd September 1987 / ed. by John Turner ... UK LDA Users Group},
  publisher = {Springer},
  address   = {Berlin [u.a.]},
  isbn      = {3540187561},
  pages     = {VII, 601 S : Ill., graph. Darst.},
  year      = {1987},
  language  = {en}
}
@article{vonHaefenKrautwaldStolleetal.2022,
  author    = {von H{\"a}fen, Hajo and Krautwald, Clemens and Stolle, Jacob and Bung, Daniel Bernhard and Goseberg, Nils},
  title     = {Overland flow of broken solitary waves over a two-dimensional coastal plane},
  series = {Coastal Engineering},
  volume    = {175},
  journal   = {Coastal Engineering},
  number    = {August},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1872-7379},
  doi       = {10.1016/j.coastaleng.2022.104125},
  pages     = {14 Seiten},
  year      = {2022},
  abstract  = {Landslides, rock falls or related subaerial and subaqueous mass slides can generate devastating impulse waves in adjacent waterbodies. Such waves can occur in lakes and fjords, or due to glacier calving in bays or at steep ocean coastlines. Infrastructure and residential houses along coastlines of those waterbodies are often situated on low elevation terrain, and are potentially at risk from inundation. Impulse waves, running up a uniform slope and generating an overland flow over an initially dry adjacent horizontal plane, represent a frequently found scenario, which needs to be better understood for disaster planning and mitigation. This study presents a novel set of large-scale flume test focusing on solitary waves propagating over a 1:14.5 slope and breaking onto a horizontal section. Examining the characteristics of overland flow, this study gives, for the first time, insight into the fundamental process of overland flow of a broken solitary wave: its shape and celerity, as well as its momentum when wave breaking has taken place beforehand.},
  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}
}
@article{BayonValeroGarciaBartualetal.2016,
  author    = {Bayon, Arnau and Valero, Daniel and Garcia-Bartual, Rafael and Vall{\´e}s-Mor{\´a}n, Francisco Jos{\´e} and L{\´o}pez-Jim{\´e}nez, P. Amparo},
  title     = {Performance assessment of OpenFOAM and FLOW-3D in the numerical modeling of a low Reynolds number hydraulic jump},
  series = {Environmental Modelling \& Software},
  volume    = {80},
  journal   = {Environmental Modelling \& Software},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1364-8152},
  doi       = {10.1016/j.envsoft.2016.02.018},
  pages     = {322 -- 335},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{BienerSasseBoekers1999,
  author    = {Biener, Ernst and Sasse, T. and B{\"o}kers, H.},
  title     = {Preliminary or final capping of sanitary landfills? : Technical and economical aspects},
  series = {Sardinia 99 : proceedings / Seventh International Waste Management and Landfill Symposium, [4 - 8 October 1999, S. Margherita di Pula, Cagliari, Sardinia, Italy]. Ed.: Thomas H. Christensen. - Bd. 3 : Barriers, waste mechanics and landfill design},
  journal   = {Sardinia 99 : proceedings / Seventh International Waste Management and Landfill Symposium, [4 - 8 October 1999, S. Margherita di Pula, Cagliari, Sardinia, Italy]. Ed.: Thomas H. Christensen. - Bd. 3 : Barriers, waste mechanics and landfill design},
  publisher = {CISA, Environmental Sanitary Engineering Centre},
  address   = {Cagliari},
  pages     = {287 -- 294},
  year      = {1999},
  language  = {en}
}
@article{BienerSasseKonertz1993,
  author    = {Biener, Ernst and Sasse, T. and Konertz, K.},
  title     = {Preparation of mineral sealing materials for landfills by different processing technologies / Sasse, T. ; Biener, E. ; Konertz, K.},
  series = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1},
  journal   = {Sardinia 93 : Fourth International Landfill Symposium "Barrier systems, environmental aspects, upgrading and remediation, siting, monofills, effects of waste pretreatment, landfilling in developing countries" ; 11 - 15 October 1993, S. Margherita di Pula (Cagliari), Sardinia, Italy ; proceedings / coord. by Thomas H. Christensen ... - Bd. 1},
  publisher = {CISA, Environmental Sanitary Engineering Centre},
  address   = {Cagliari},
  pages     = {275 -- 283},
  year      = {1993},
  language  = {en}
}
@article{GosslaSato1998,
  author    = {Gossla, Ulrich and Sato, R.},
  title     = {Present production circumstances of aggregate in Germany / Sato, R.; Gossla, U.},
  series = {Cement \& Concrete (1998)},
  journal   = {Cement \& Concrete (1998)},
  pages     = {146 -- 153},
  year      = {1998},
  language  = {en}
}
@article{HoettgesArnoldRouve1992,
  author    = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard},
  title     = {Profiles of Mixing Coefficient in Compound Open Channel},
  series = {Flow modeling and turbulence measurements : [... a collection of lectures and papers presented at the Fourth International Symposium on Refined Flow Modelling and Turbulence Measurements held in Wuhan, People's Republic of China, on September 20-23, 1990]},
  journal   = {Flow modeling and turbulence measurements : [... a collection of lectures and papers presented at the Fourth International Symposium on Refined Flow Modelling and Turbulence Measurements held in Wuhan, People's Republic of China, on September 20-23, 1990]},
  publisher = {Hemisphere Publ. Corp.},
  address   = {Washington, DC [u.a.]},
  isbn      = {1-56032-209-8},
  pages     = {XVII, 773 S. : graph. Darst.},
  year      = {1992},
  language  = {en}
}
@article{Hoettges2017,
  author    = {H{\"o}ttges, J{\"o}rg},
  title     = {QKan - Management of drainage system data with QGIS},
  series = {Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings},
  volume    = {17},
  journal   = {Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings},
  number    = {Article 13},
  pages     = {95 -- 100},
  year      = {2017},
  language  = {en}
}
@article{BienerSasse1993,
  author    = {Biener, Ernst and Sasse, T.},
  title     = {Quality improvements in the construction of multilayer covers},
  series = {G{\´e}ologie et confinement des d{\´e}chets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. R{\´e}d. Marcel Arnould},
  journal   = {G{\´e}ologie et confinement des d{\´e}chets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. R{\´e}d. Marcel Arnould},
  publisher = {Balkema},
  address   = {Rotterdam [u.a.]},
  isbn      = {90-5410-330-2},
  pages     = {309 -- 312},
  year      = {1993},
  language  = {en}
}
@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}
}
@article{ValeroBung2018,
  author    = {Valero, Daniel and Bung, Daniel B.},
  title     = {Reformulating self-aeration in hydraulic structures: Turbulent growth of free surface perturbations leading to air entrainment},
  series = {International Journal of Multiphase Flow},
  volume    = {100},
  journal   = {International Journal of Multiphase Flow},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9322},
  doi       = {10.1016/j.ijmultiphaseflow.2017.12.011},
  pages     = {127 -- 142},
  year      = {2018},
  abstract  = {A new formulation for the prediction of free surface dynamics related to the turbulence occurring nearby is proposed. This formulation, altogether with a breakup criterion, can be used to compute the inception of self-aeration in high velocity flows like those occurring in hydraulic structures. Assuming a simple perturbation geometry, a kinematic and a non-linear momentum-based dynamic equation are formulated and forces acting on a control volume are approximated. Limiting steepness is proposed as an adequate breakup criterion. Role of the velocity fluctuations normal to the free surface is shown to be the main turbulence quantity related to self-aeration and the role of the scales contained in the turbulence spectrum are depicted. Surface tension force is integrated accounting for large displacements by using differential geometry for the curvature estimation. Gravity and pressure effects are also contemplated in the proposed formulation. The obtained equations can be numerically integrated for each wavelength, hence resulting in different growth rates and allowing computation of the free surface roughness wavelength distribution. Application to a prototype scale spillway (at the Aviemore dam) revealed that most unstable wavelength was close to the Taylor lengthscale. Amplitude distributions have been also obtained observing different scaling for perturbations stabilized by gravity or surface tension. The proposed theoretical framework represents a new conceptualization of self-aeration which explains the characteristic rough surface at the non-aerated region as well as other previous experimental observations which remained unresolved for several decades.},
  language  = {en}
}