@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{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{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{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{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{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{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} } @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{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} } @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} } @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{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} } @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} } @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{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{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} } @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} } @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} }