@inproceedings{AhmedSchlenkhoffBung2011,
  author    = {Ahmed, H. and Schlenkhoff, A. and Bung, Daniel Bernhard},
  title     = {Hydrodynamic characteristics of vertical slotted wall breakwaters},
  series = {Balance and uncertainty - water in a changing world : proceedings of the 34th IAHR world congress ; 33rd Hydrology and Water Resources Symposium ; 10th Conference on Hydraulics in Water Engineering ; 26 June - 1 July 2011, Brisbane, Australia},
  booktitle = {Balance and uncertainty - water in a changing world : proceedings of the 34th IAHR world congress ; 33rd Hydrology and Water Resources Symposium ; 10th Conference on Hydraulics in Water Engineering ; 26 June - 1 July 2011, Brisbane, Australia},
  organization    = {International Association for Hydraulic Engineering and Research},
  isbn      = {978-0-85825-868-6},
  pages     = {1179 -- 1186},
  year      = {2011},
  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{Biener1985,
  author    = {Biener, Ernst},
  title     = {Rehabilitation of old gravity dams},
  series = {[Transactions] : proceedings of fifteenth international congress on large dams ; 24 - 28 Juin 1985, Lausanne, Suisse = Quinzieme Congres International des Grands Barrages. - Bd. 4},
  journal   = {[Transactions] : proceedings of fifteenth international congress on large dams ; 24 - 28 Juin 1985, Lausanne, Suisse = Quinzieme Congres International des Grands Barrages. - Bd. 4},
  publisher = {Intern. Commission on Large Dams},
  address   = {Paris},
  pages     = {Q 59, R.2, S. 21 -- 23},
  year      = {1985},
  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{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{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{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{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{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{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{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{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{BienerSasseWernhoff2003,
  author    = {Biener, Ernst and Sasse, T. and Wernhoff, T.},
  title     = {Using harbour dredged material for combination sealing of the former Bockhorner Weg disposal site in Bremen, Germany},
  series = {Proceedings of the International Harbour Congress. 13 (2003)},
  journal   = {Proceedings of the International Harbour Congress. 13 (2003)},
  pages     = {101 -- 109},
  year      = {2003},
  language  = {en}
}
@article{BienerWemhoffBethke1995,
  author    = {Biener, Ernst and Wemhoff, T. and Bethke, H.},
  title     = {Stability and settlement problems based on the example of the Blockland landfill in Bremen},
  series = {Sardinia 95 : Fifth International Landfill Symposium ; (2 - 6 October 1995, S. Margheritadi Pula - Cagliari, Sardinia, Italy) ; proceedings / coord.: Thomas H. Christensen ... - Bd. 2 : Siting, lining, drainage \& landfill mechanics},
  journal   = {Sardinia 95 : Fifth International Landfill Symposium ; (2 - 6 October 1995, S. Margheritadi Pula - Cagliari, Sardinia, Italy) ; proceedings / coord.: Thomas H. Christensen ... - Bd. 2 : Siting, lining, drainage \& landfill mechanics},
  publisher = {CISA, Environmental Sanitary Engineering Centre},
  address   = {Cagliari},
  pages     = {843 -- 853},
  year      = {1995},
  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}
}
@inproceedings{BlankeSchmidtGoettscheetal.2022,
  author    = {Blanke, Tobias and Schmidt, Katharina S. and G{\"o}ttsche, Joachim and D{\"o}ring, Bernd and Frisch, J{\´e}r{\^o}me and van Treeck, Christoph},
  title     = {Time series aggregation for energy system design: review and extension of modelling seasonal storages},
  series = {Energy Informatics},
  volume    = {5},
  booktitle = {Energy Informatics},
  number    = {1, Article number: 17},
  editor    = {Weidlich, Anke and Neumann, Dirk and Gust, Gunther and Staudt, Philipp and Sch{\"a}fer, Mirko},
  publisher = {Springer Nature},
  issn      = {2520-8942},
  doi       = {10.1186/s42162-022-00208-5},
  pages     = {14 Seiten},
  year      = {2022},
  abstract  = {Using optimization to design a renewable energy system has become a computationally demanding task as the high temporal fluctuations of demand and supply arise within the considered time series. The aggregation of typical operation periods has become a popular method to reduce effort. These operation periods are modelled independently and cannot interact in most cases. Consequently, seasonal storage is not reproducible. This inability can lead to a significant error, especially for energy systems with a high share of fluctuating renewable energy. The previous paper, "Time series aggregation for energy system design: Modeling seasonal storage", has developed a seasonal storage model to address this issue. Simultaneously, the paper "Optimal design of multi-energy systems with seasonal storage" has developed a different approach. This paper aims to review these models and extend the first model. The extension is a mathematical reformulation to decrease the number of variables and constraints. Furthermore, it aims to reduce the calculation time while achieving the same results.},
  language  = {en}
}
@inproceedings{Bung2013,
  author    = {Bung, Daniel Bernhard},
  title     = {Air-water surface roughness in self-aerated stepped spillway flows},
  series = {35th IAHR world congress : 8.-13.9.2013, Chengdu, China},
  booktitle = {35th IAHR world congress : 8.-13.9.2013, Chengdu, China},
  publisher = {Tsinghua Univ. Press},
  address   = {Beijing},
  organization    = {International Association for Hydraulic Engineering and Research},
  pages     = {Artikelkennnummer: A11045},
  year      = {2013},
  language  = {en}
}
@inproceedings{Bung2011,
  author    = {Bung, Daniel Bernhard},
  title     = {Non-intrusive measuring of air-water flow properties in self-aerated stepped spillway flow},
  series = {Balance and uncertainty - water in a changing world : proceedings of the 34th IAHR world congress ; 33rd Hydrology and Water Resources Symposium ; 10th Conference on Hydraulics in Water Engineering ; 26 June - 1 July 2011, Brisbane, Australia},
  booktitle = {Balance and uncertainty - water in a changing world : proceedings of the 34th IAHR world congress ; 33rd Hydrology and Water Resources Symposium ; 10th Conference on Hydraulics in Water Engineering ; 26 June - 1 July 2011, Brisbane, Australia},
  organization    = {International Association for Hydraulic Engineering and Research},
  isbn      = {978-0-85825-868-6},
  pages     = {2380 -- 2387},
  year      = {2011},
  language  = {en}
}
@inproceedings{Bung2010,
  author    = {Bung, Daniel Bernhard},
  title     = {A comparative study of self-aerated stepped spillway and smooth invert chute flow: the effect of step-induced macro roughness},
  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     = {451 -- 456},
  year      = {2010},
  language  = {en}
}
@inproceedings{Bung2012,
  author    = {Bung, Daniel Bernhard},
  title     = {Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters},
  series = {2nd European IAHR congress : 27. - 29. June 2012, M{\"u}nchen},
  booktitle = {2nd European IAHR congress : 27. - 29. June 2012, M{\"u}nchen},
  publisher = {Lehrstuhl u. Versuchsanst. f{\"u}r Wasserbau u. Wasserwirtschaft d. TU M{\"u}nchen},
  address   = {M{\"u}nchen},
  organization    = {International Association for Hydraulic Engineering and Research},
  isbn      = {978-3-943683-03-5},
  pages     = {Artikelkennnummer: B15},
  year      = {2012},
  language  = {en}
}
@article{Bung2013,
  author    = {Bung, Daniel Bernhard},
  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{Bung2011,
  author    = {Bung, Daniel Bernhard},
  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}
}
@incollection{Bung2015,
  author    = {Bung, Daniel Bernhard},
  title     = {Laboratory models of free-surface flows},
  series = {Rivers - physical, fluvial and environmental processes},
  booktitle = {Rivers - physical, fluvial and environmental processes},
  editor    = {Rowinski, Pawel},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-319-17718-2 ; 978-3-319-17719-9},
  doi       = {10.1007/978-3-319-17719-9_9},
  pages     = {213 -- 228},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@inproceedings{Bung2014,
  author    = {Bung, Daniel Bernhard},
  title     = {Observations on non-aerated flow and air entrainment on moderately sloped stepped spillways},
  series = {7th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : 8. - 12. Sept. 2014, Hannover},
  booktitle = {7th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering : 8. - 12. Sept. 2014, Hannover},
  organization    = {Chinese-German Joint Symposium on Hydraulic and Ocean Engineering <7, 2014, Hannover>},
  pages     = {1 -- 8},
  year      = {2014},
  language  = {en}
}
@article{Bung2021,
  author    = {Bung, Daniel Bernhard},
  title     = {Extreme flooding in Western Germany: some thoughts on hazards, return periods and risk},
  series = {Hydrolink},
  journal   = {Hydrolink},
  number    = {4},
  publisher = {International Association for Hydro-Environment Engineering and Research (IAHR)},
  address   = {Madrid},
  pages     = {108 -- 113},
  year      = {2021},
  abstract  = {The low-pressure system Bernd involved extreme rainfalls in the Western part of Germany in July 2021, resulting in major floods, severe damages and a tremendous number of casualties. Such extreme events are rare and full flood protection can never be ensured with reasonable financial means. But still, this event must be starting point to reconsider current design concepts. This article aims at sharing some thoughts on potential hazards, the selection of return periods and remaining risk with the focus on Germany.},
  language  = {en}
}
@phdthesis{Bung2023,
  author    = {Bung, Daniel Bernhard},
  title     = {Imaging techniques for investigation of free-surface flows in hydraulic laboratories},
  doi       = {10.25926/BUW/0-172},
  pages     = {XXIII, 218 Seiten},
  year      = {2023},
  abstract  = {This thesis aims at the presentation and discussion of well-accepted and new imaging techniques applied to different types of flow in common hydraulic engineering environments. All studies are conducted in laboratory conditions and focus on flow depth and velocity measurements. Investigated flows cover a wide range of complexity, e.g. propagation of waves, dam-break flows, slightly and fully aerated spillway flows as well as highly turbulent hydraulic jumps. Newimagingmethods are compared to different types of sensorswhich are frequently employed in contemporary laboratory studies. This classical instrumentation as well as the general concept of hydraulic modeling is introduced to give an overview on experimental methods. Flow depths are commonly measured by means of ultrasonic sensors, also known as acoustic displacement sensors. These sensors may provide accurate data with high sample rates in case of simple flow conditions, e.g. low-turbulent clear water flows. However, with increasing turbulence, higher uncertainty must be considered. Moreover, ultrasonic sensors can provide point data only, while the relatively large acoustic beam footprint may lead to another source of uncertainty in case of relatively short, highly turbulent surface fluctuations (ripples) or free-surface air-water flows. Analysis of turbulent length and time scales of surface fluctuations from point measurements is also difficult. Imaging techniques with different dimensionality, however, may close this gap. It is shown in this thesis that edge detection methods (known from computer vision) may be used for two-dimensional free-surface extraction (i.e. from images taken through transparant sidewalls in laboratory flumes). Another opportunity in hydraulic laboratory studies comes with the application of stereo vision. Low-cost RGB-D sensors can be used to gather instantaneous, three-dimensional free-surface elevations, even in flows with very high complexity (e.g. aerated hydraulic jumps). It will be shown that the uncertainty of these methods is of similar order as for classical instruments. Particle Image Velocimetry (PIV) is a well-accepted and widespread imaging technique for velocity determination in laboratory conditions. In combination with high-speed cameras, PIV can give time-resolved velocity fields in 2D/3D or even as volumetric flow fields. PIV is based on a cross-correlation technique applied to small subimages of seeded flows. The minimum size of these subimages defines the maximum spatial resolution of resulting velocity fields. A derivative of PIV for aerated flows is also available, i.e. the so-called Bubble Image Velocimetry (BIV). This thesis emphasizes the capacities and limitations of both methods, using relatively simple setups with halogen and LED illuminations. It will be demonstrated that PIV/BIV images may also be processed by means of Optical Flow (OF) techniques. OF is another method originating from the computer vision discipline, based on the assumption of image brightness conservation within a sequence of images. The Horn-Schunck approach, which has been first employed to hydraulic engineering problems in the studies presented herein, yields dense velocity fields, i.e. pixelwise velocity data. As discussed hereinafter, the accuracy of OF competes well with PIV for clear-water flows and even improves results (compared to BIV) for aerated flow conditions. In order to independently benchmark the OF approach, synthetic images with defined turbulence intensitiy are used. Computer vision offers new opportunities that may help to improve the understanding of fluid mechanics and fluid-structure interactions in laboratory investigations. In prototype environments, it can be employed for obstacle detection (e.g. identification of potential fish migration corridors) and recognition (e.g. fish species for monitoring in a fishway) or surface reconstruction (e.g. inspection of hydraulic structures). It can thus be expected that applications to hydraulic engineering problems will develop rapidly in near future. Current methods have not been developed for fluids in motion. Systematic future developments are needed to improve the results in such difficult conditions.},
  language  = {en}
}
@article{BungCrookstonValero2020,
  author    = {Bung, Daniel Bernhard and Crookston, Brian M. and Valero, Daniel},
  title     = {Turbulent free-surface monitoring with an RGB-D sensor: the hydraulic jump case},
  series = {Journal of Hydraulic Research},
  journal   = {Journal of Hydraulic Research},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {1814-2079},
  doi       = {10.1080/00221686.2020.1844810},
  year      = {2020},
  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}
}
@inproceedings{BungHildebrandtOerteletal.2008,
  author    = {Bung, Daniel Bernhard and Hildebrandt, Arndt and Oertel, Mario and Schlenkhoff, Andreas and Schlurmann, Torsten},
  title     = {Bore propagation over a submerged horizontal plate by physical and numerical simulation},
  series = {Coastal engineering 2008 : proceedings of the 31st international conference; Hamburg, Germany, 31 August - 5 September 2008 ; Vol. 4},
  booktitle = {Coastal engineering 2008 : proceedings of the 31st international conference; Hamburg, Germany, 31 August - 5 September 2008 ; Vol. 4},
  editor    = {McKee Smith, Jane},
  isbn      = {9814277401 ; 9789814277402},
  pages     = {3542 -- 3553},
  year      = {2008},
  language  = {en}
}
@inproceedings{BungOertelSchlenkhoffetal.2010,
  author    = {Bung, Daniel Bernhard and Oertel, M. and Schlenkhoff, A. and Schlurmann, Torsten},
  title     = {Flash flood awareness and prevention in Germany},
  series = {Early warning for flash floods : international workshop, Praha 2011 : workshop proceedings},
  booktitle = {Early warning for flash floods : international workshop, Praha 2011 : workshop proceedings},
  editor    = {Obrusnik, Ivan},
  organization    = {Czech Hydrometeorological Institute},
  isbn      = {978-80-86690-91-9},
  pages     = {34 -- 40},
  year      = {2010},
  language  = {en}
}
@inproceedings{BungOertel2014,
  author    = {Bung, Daniel Bernhard and Oertel, Mario},
  title     = {Manipulation of non-aerated cavity flow on a stepped spillway model},
  series = {3rd European IAHR Congress : April 14 - 16, 2014, Porto},
  booktitle = {3rd European IAHR Congress : April 14 - 16, 2014, Porto},
  publisher = {Univ. of Porto},
  address   = {Porto},
  organization    = {International Association of Hydro-Environment Engineering and Research},
  year      = {2014},
  language  = {en}
}
@inproceedings{BungOertel2019,
  author    = {Bung, Daniel Bernhard and Oertel, Mario},
  title     = {Wave breaking over a submerged horizontal plate: Optical Flow, LES and RANS},
  series = {E-proceedings of the 38th IAHR World Congress September 1-6, 2019, Panama City, Panama},
  booktitle = {E-proceedings of the 38th IAHR World Congress September 1-6, 2019, Panama City, Panama},
  doi       = {10.3850/38WC092019-0509},
  pages     = {3690 -- 3698},
  year      = {2019},
  language  = {en}
}
@inproceedings{BungPagliara2013,
  author    = {Bung, Daniel Bernhard 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{BungSchlenkhoff2008,
  author    = {Bung, Daniel Bernhard 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}
}
@inproceedings{BungSchlenkhoff2010,
  author    = {Bung, Daniel Bernhard and Schlenkhoff, Andreas},
  title     = {Self-aerated skimming flow on embankment stepped spillways : the effect of additional micro-roughness on energy dissipation and oxygen transfer},
  series = {Proceedings from first IAHR European congress : May 2010, Edinburgh},
  booktitle = {Proceedings from first IAHR European congress : May 2010, Edinburgh},
  publisher = {Heriot-Watt University, School of the Built Environment},
  address   = {Edinburgh},
  organization    = {International Association for Hydraulic Engineering and Research},
  isbn      = {9780956595102},
  pages     = {Artikelkennnummer HSIIId},
  year      = {2010},
  language  = {en}
}
@inproceedings{BungSchlenkhoffOertel2009,
  author    = {Bung, Daniel Bernhard and Schlenkhoff, Andreas and Oertel, M.},
  title     = {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{BungSunMeirelesetal.2012,
  author    = {Bung, Daniel Bernhard and Sun, Q. and Meireles, I. and Matos, J. and Viseu, T.},
  title     = {USBR type III stilling basin performance for steep stepped spillways},
  series = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto},
  booktitle = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto},
  organization    = {International Symposium on Hydraulic Structures <4, 2012, Porto>},
  isbn      = {978-989-8509-01-7},
  pages     = {Elektronisch publiziert},
  year      = {2012},
  language  = {en}
}
@inproceedings{BungTullis2018,
  author    = {Bung, Daniel Bernhard and Tullis, Blake},
  title     = {Hydraulic Structures - ISHS2018 in Perspective},
  series = {7th IAHR International Symposium on Hydraulic Structures, Aachen, Germany, 15-18 May},
  booktitle = {7th IAHR International Symposium on Hydraulic Structures, Aachen, Germany, 15-18 May},
  isbn      = {978-0-692-13277-7},
  doi       = {10.15142/T3WH2B},
  pages     = {9 seiten},
  year      = {2018},
  language  = {en}
}
@inproceedings{BungValero2015,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Image processing for bubble image velocimetry in self-aerated flows},
  series = {E-proceedings of the 36th IAHR World Congress 28 June - 3 July, 2015, The Hague, the Netherlands},
  booktitle = {E-proceedings of the 36th IAHR World Congress 28 June - 3 July, 2015, The Hague, the Netherlands},
  organization    = {IAHR World Congress <36, 2015, Den Haag>},
  pages     = {1 -- 8},
  year      = {2015},
  language  = {en}
}
@inproceedings{BungValero2016,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Application of the optical flow method to velocity determination in hydraulic structure models},
  series = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  booktitle = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  editor    = {Crookston, B. and Tullis, B.},
  isbn      = {978-1-884575-75-4},
  doi       = {10.15142/T3150628160853},
  pages     = {223 -- 232},
  year      = {2016},
  language  = {en}
}
@article{BungValero2016,
  author    = {Bung, Daniel Bernhard 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}
}
@inproceedings{BungValero2016,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Image processing techniques for velocity estimation in highly aerated flows: bubble image velocimetry vs. optical flow},
  series = {Sustainable Hydraulics in the Era of Global Change : Proceedings of the 4th IAHR Europe Congress (Liege, Belgium, 27-29 July 2016)},
  booktitle = {Sustainable Hydraulics in the Era of Global Change : Proceedings of the 4th IAHR Europe Congress (Liege, Belgium, 27-29 July 2016)},
  editor    = {Dewals, Benjamin},
  publisher = {CRC Press},
  isbn      = {978-1-138-02977-4},
  doi       = {10.1201/b21902-31},
  pages     = {151 -- 157},
  year      = {2016},
  language  = {en}
}
@inproceedings{BungValero2017,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {FlowCV - An open-source toolbox for computer vision applications in turbulent flows},
  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     = {5356 -- 5365},
  year      = {2017},
  language  = {en}
}
@article{BungValero2018,
  author    = {Bung, Daniel Bernhard 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{BuehlerLeandroBungetal.2015,
  author    = {B{\"u}hler, P. and Leandro, J. and Bung, Daniel Bernhard and Lopes, P. and Carvalho, R.},
  title     = {Measuring void fraction of a stepped spillway with non-intrusive methods using different image resolutions},
  series = {2nd International Workshop on Hydraulic Structures : Data Validation : Coimbra, Portugal, 8-9 May 2015},
  booktitle = {2nd International Workshop on Hydraulic Structures : Data Validation : Coimbra, Portugal, 8-9 May 2015},
  organization    = {International Workshop on Hydraulic Structures : Data Validation <2, 2015, Coimbra>},
  pages     = {1 -- 8},
  year      = {2015},
  language  = {en}
}
@incollection{ChansonBungMatos2015,
  author    = {Chanson, Hubert and Bung, Daniel Bernhard and Matos, J.},
  title     = {Stepped spillways and cascades},
  series = {Energy dissipation in hydraulic structures / Hubert Chanson (ed.)},
  booktitle = {Energy dissipation in hydraulic structures / Hubert Chanson (ed.)},
  publisher = {CRC Press},
  address   = {Boca Raton, Fla. [u.a.]},
  isbn      = {978-1-138-02755-8 (print) ; 978-1-315-68029-3 (e-Book)},
  pages     = {45 -- 64},
  year      = {2015},
  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{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}
}