TY - JOUR A1 - Biener, Ernst A1 - Rouvé, G. T1 - Behaviour and maintenance of some old masonry gravity dams JF - Safety of dams : proceedings of the International Conference on Safety of Dams, Coimbra, 23-28 April 1984 / ed. by J. Laginha Serafim. - [Hauptbd.] Y1 - 1984 SN - 90-6191-522-8 N1 - International Conference on Safety of Dams <1984, Coimbra> ; ISBN Set: 90-6191-521-X SP - 101 EP - 106 PB - Rotterdam [u.a.] CY - Balkema ER - TY - JOUR A1 - Biener, Ernst T1 - Rehabilitation of old gravity dams JF - [Transactions] : proceedings of fifteenth international congress on large dams ; 24 - 28 Juin 1985, Lausanne, Suisse = Quinzieme Congres International des Grands Barrages. - Bd. 4 Y1 - 1985 N1 - International Congress on Large Dams <15, 1985, Paris> SP - Q 59, R.2, S. 21 EP - 23 PB - Intern. Commission on Large Dams CY - Paris ER - TY - JOUR A1 - Höttges, Jörg A1 - Ritterbach, E. A1 - Els, H. T1 - Optical Improvement of LDV-Measurement in Pipe Flow / Ritterbach, E.; J. Höttges; H. Els JF - 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 Y1 - 1987 SN - 3540187561 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. T1 - Experience with new techniques in slurry cutoff wall construction JF - ISWA 88, proceedings of the 5th International Solid Wastes Conference : September 11 - 16th, 1988, Copenhagen, Denmark / ed. by Lizzi Andersen ... - Vol. 1 : Oral presentations Y1 - 1988 SN - 0-12-058451-4 N1 - International Solid Wastes Conference <5, 1988, København> ; International Solid Wastes and Public Cleansing Association SP - 41 EP - 46 PB - Acad. Press CY - London [u.a.] ER - TY - JOUR A1 - Höttges, Jörg A1 - Arnold, Uwe A1 - Rouvé, Gerhard T1 - Combined Digital Image and Finite Element Analysis of Mixing in Compound Open Channel Flow / Arnold, U.; J. Höttges; G. Rouvé JF - 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 Y1 - 1989 SN - 4-946443-03-7 N1 - International Symposium on Refined Flow Modelling and Turbulence Measurements <3, 1988, Tōkyō> SP - 569 EP - 576 PB - Universal Acad. Press CY - Tokyo ER - TY - JOUR A1 - Höttges, Jörg T1 - Turbulence and Mixing Mechanics in Compound Open Channel Flow / Arnold, Uwe; Höttges, Jörg; Rouvé, Gerhard JF - On cutoff ratios of curved channels : paper presented at the 23rd Congress of the IAHR, Ottawa, Canada, August 21 - 25, 1989 / G. J. Klaassen; B. H. J.van Zanten Y1 - 1990 N1 - Congress of the IAHR ; (23 : ; 1989.08.21-25 : ; Ottawa) PB - Delft Hydraulics CY - Delft ER - TY - JOUR A1 - Höttges, Jörg A1 - Arnold, Uwe A1 - Rouvé, Gerhard T1 - Profiles of Mixing Coefficient in Compound Open Channel JF - 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] Y1 - 1992 SN - 1-56032-209-8 N1 - International Symposium on Refined Flow Modelling and Turbulence Measurements <4, 1990, Wuhan> PB - Hemisphere Publ. Corp. CY - Washington, DC [u.a.] ER - TY - JOUR A1 - Höttges, Jörg T1 - A Full Finite Element Solution for the Unsteady Advection-Diffusion Equation JF - 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 Y1 - 1992 SN - 185312169X N1 - International Conference on Computational Methods in Water Resources ; (9, 1992, Denver, Colo.) PB - Computational Mechanics Publications [u.a.] CY - Southampton [u.a.] ER - TY - JOUR A1 - Höttges, Jörg A1 - Feldhaus, R. A1 - Brockhaus, T. A1 - Rouvé, Gerhard T1 - Finite Element Simulation of Flow and Pollution Transport applied to a Part of the River Rhine / Feldhaus, R.; J. Höttges, T. Brockhaus; G. Rouvé JF - 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 Y1 - 1992 N1 - International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters ; (2, 1992, Bradford) PB - Ashgate CY - Aldershot, Hants, UK [u.a.] ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. T1 - Construction and rehabilitation of landfill shafts JF - 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 Y1 - 1993 N1 - International Landfill Symposium <4, 1993, Santa Margherita, Pula> SP - 451 EP - 460 PB - CISA, Environmental Sanitary Engineering Centre CY - Cagliari ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. T1 - Quality improvements in the construction of multilayer covers JF - Géologie et confinement des déchets toxiques : actes du symposium international, 8 - 11 juin 1993 / GEOCONFINE 93, Montpellier, France. Réd. Marcel Arnould Y1 - 1993 SN - 90-5410-330-2 N1 - Geoconfine <1993, Montpellier> ; Paralellt.: Geology and confinement of toxic wastes SP - 309 EP - 312 PB - Balkema CY - Rotterdam [u.a.] ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. A1 - Konertz, K. T1 - Preparation of mineral sealing materials for landfills by different processing technologies / Sasse, T. ; Biener, E. ; Konertz, K. JF - 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 Y1 - 1993 N1 - International Landfill Symposium <4, 1993, Santa Margherita, Pula> SP - 275 EP - 283 PB - CISA, Environmental Sanitary Engineering Centre CY - Cagliari ER - TY - JOUR A1 - Höttges, Jörg A1 - Arnold, Uwe A1 - Rouvé, Gerhard T1 - Measurement of transverse mixing using digital image acquisition JF - Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven Y1 - 1994 SN - 0471941425 PB - Wiley CY - Chichester [u.a.] ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. T1 - Construction of composite lining systems under unfavourable weather conditions JF - Landfilling of waste: barriers / ed. by T. H. Christensen; R. Cossu; R. Stegmann. - 1. Aufl. Y1 - 1994 SN - 0419159908 SP - 183 EP - 200 PB - Spon CY - London [u.a.] ER - TY - JOUR A1 - Biener, Ernst A1 - Wemhoff, T. A1 - Bethke, H. T1 - Stability and settlement problems based on the example of the Blockland landfill in Bremen JF - 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 Y1 - 1995 N1 - International Landfill Symposium <5, 1995, Santa Margherita, Pula> SP - 843 EP - 853 PB - CISA, Environmental Sanitary Engineering Centre CY - Cagliari ER - TY - JOUR A1 - Biener, Ernst A1 - Boyken, P. A1 - Sasse, T. T1 - Integrated dredged material management system of Bremen-Seehausen JF - 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 Y1 - 1997 N1 - International Landfill Symposium <6, 1997, Santa Margherita, Pula> SP - 497 EP - 502 PB - CISA, Environmental Sanitary Engineering Centre CY - Cagliari ER - TY - JOUR A1 - Gossla, Ulrich A1 - Sato, R. T1 - Present production circumstances of aggregate in Germany / Sato, R.; Gossla, U. JF - Cement & Concrete (1998) Y1 - 1998 N1 - auf Japanisch SP - 146 EP - 153 ER - TY - JOUR A1 - Biener, Ernst A1 - Boyken, P. A1 - Sasse, T. A1 - Arnold, J. T1 - Geotechnical aspects of the construction of the integrated harbour sludge management system in Bremen-Seehausen / P. Boyken ; E. Biener ; T. Sasse ; J. Arnold JF - 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 Y1 - 1999 SN - 90-5809-049-3 N1 - European Conference on Soil Mechanics and Geotechnical Engineering <12, 1999, Amsterdam> SP - 909 EP - 914 PB - Balkema CY - Rotterdam ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. A1 - Arnold, J. A1 - Woltering, S. T1 - New treatment of harbour sludge in Bremen and Bremerhaven / E. Biener ; T. Sasse ; J. Arnold ; S. Woltering ; N. Binder JF - 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 Y1 - 1999 SN - 9076019118 N1 - CATS <4, 1999, Anvers> SP - 115 EP - 122 PB - Technolog. Inst. CY - Anvers ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. A1 - Bökers, H. T1 - Preliminary or final capping of sanitary landfills? : Technical and economical aspects JF - 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 Y1 - 1999 N1 - International Waste Management and Landfill Symposium <7, 1999, Cagliari> SP - 287 EP - 294 PB - CISA, Environmental Sanitary Engineering Centre CY - Cagliari ER - TY - JOUR A1 - Jochim, Haldor E. T1 - Charging rail operators for delays – how not to do it JF - Networks for mobility : International Symposium, September 18 - 20, 2002, Stuttgart, Germany ; proceedings / University of Stuttgart, Centre of Transporation Research (FOVUS). W. Möhlenbrink ... (eds.) Y1 - 2002 SN - 3893010858 N1 - International Symposium ; (2002.09.18-20 : ; Stuttgart) PB - FOVUS CY - Stuttgart ER - TY - JOUR A1 - Biener, Ernst A1 - Bethke, H. A1 - Sasse, T. A1 - Wernhoff, T. T1 - Alternative landfill capping using locally available recycled material JF - Land contamination & reclamation. 14 (2003), H. 4 Y1 - 2003 SN - 0967-0513 SP - 419 EP - 427 ER - TY - JOUR A1 - Biener, Ernst A1 - Sasse, T. A1 - Wernhoff, T. T1 - Using harbour dredged material for combination sealing of the former Bockhorner Weg disposal site in Bremen, Germany JF - Proceedings of the International Harbour Congress. 13 (2003) Y1 - 2003 N1 - International Harbour Congress <13, 2003, Antwerpen> SP - 101 EP - 109 ER - TY - JOUR A1 - Jochim, Haldor E. T1 - A traffic resistance model of long-distance travel JF - 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 Y1 - 2004 SN - 3-89301-180-3 N1 - International Symposium on Networks for Mobility (2, 2004, Stuttgart) PB - FOVUS CY - Stuttgart ER - TY - JOUR A1 - Kolymbas, Dimitrios A1 - Fellin, W. A1 - Kirsch, Ansgar T1 - Squeezing due to stress relaxation in foliated rock JF - International journal for numerical and analytical methods in geomechanics Y1 - 2006 U6 - http://dx.doi.org/10.1002/nag.530 SN - 1096-9853 (E-Journal); 0363-9061 (Print) VL - Vol. 30 IS - Iss. 13 SP - 1357 EP - 1367 ER - TY - JOUR A1 - Kirsch, Ansgar T1 - Experimental investigation of the face stability of shallow tunnels in sand JF - Acta Geotechnica N2 - 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 Léca/Dormieux showed the best agreement to the measurements. Y1 - 2010 U6 - http://dx.doi.org/10.1007/s11440-010-0110-7 SN - 1861-1125 VL - 5 IS - 1 SP - 43 EP - 62 PB - Springer CY - Berlin ER - TY - JOUR A1 - Fellin, Wolfgang A1 - King, Julian A1 - Kirsch, Ansgar A1 - Oberguggenberger, Michael T1 - Uncertainty modelling and sensitivity analysis of tunnel face stability JF - Structural safety N2 - This paper proposes an approach to the choice and evaluation of engineering models with the aid of a typical application in geotechnics. An important issue in the construction of shallow tunnels, especially in weak ground conditions, is the tunnel face stability. Various theoretical and numerical models for predicting the necessary support pressure have been put forth in the literature. In this paper, we combine laboratory experiments performed at the University of Innsbruck with current methods of uncertainty and sensitivity analysis for assessing adequacy, predictive power and robustness of the models. The major issues are the handling of the twofold uncertainty of test results and of model predictions as well as the decision about what are the influential input parameters. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.strusafe.2010.06.001 SN - 0167-4730 VL - 32 IS - 6 SP - 402 EP - 410 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bung, Daniel B. T1 - Developing flow in skimming flow regime on embankment stepped spillways JF - Journal of hydraulic research Y1 - 2011 SN - 1814-2079 (E-Journal); 0022-1686 (Print) VL - Vol. 49 IS - Iss. 5 SP - 639 EP - 648 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Kirstein, Simon A1 - Müller, Karsten A1 - Walecki-Mingers, Mark A1 - Deserno, Thomas M. T1 - Robust adaptive flow line detection in sewer pipes JF - Automation in construction N2 - As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.autcon.2011.05.009 SN - 1872-7891 (E-Journal) ; 0926-5805 (Print) IS - 21 SP - 24 EP - 31 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Oertel, Mario A1 - Bung, Daniel B. T1 - Initial stage of two-dimensional dam-break waves: laboratory versus VOF JF - Journal of hydraulic research N2 - 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. KW - VOF KW - PIV KW - physical model KW - numerical model KW - drag force KW - dam-break Y1 - 2012 U6 - http://dx.doi.org/10.1080/00221686.2011.639981 SN - 1814-2079 (E-Journal); 0022-1686 (Print) VL - 50 IS - 1 SP - 89 EP - 97 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Bung, Daniel B. T1 - Non-intrusive detection of air–water surface roughness in self-aerated chute flows JF - Journal of hydraulic research Y1 - 2013 SN - 1814-2079 (E-Journal); 0022-1686 (Print) VL - Vol. 51 IS - Iss. 3 SP - 322 EP - 329 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Döring, Bernd A1 - Kendrick, C. A1 - Lawson, R. M. T1 - Thermal capacity of composite floor slabs JF - Energy and buildings Y1 - 2013 SN - 1872-6178 (E-Journal); 0378-7788 (Print) VL - Vol. 67 SP - 531 EP - 539 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Leandro, J. A1 - Bung, Daniel B. A1 - Carvalho, R. T1 - Measuring void fraction and velocity fields of a stepped spillway for skimming flow using non-intrusive methods JF - Experiments in fluids Y1 - 2014 U6 - http://dx.doi.org/10.1007/s00348-014-1732-6 SN - 0723-4864 (Print) ; 1432-1114 (Online) IS - 55 SP - Art. 1732 PB - Springer Nature CY - Heidelberg ER - TY - JOUR A1 - Döring, Bernd A1 - Reger, Vitali A1 - Kuhnhenne, Markus A1 - Feldmann, Markus A1 - Kesti, Jyrki A1 - Lawson, Mark A1 - Botti, Andrea T1 - Steel solutions for enabling zero-energy buildings JF - Steel Construction - Design and Research Y1 - 2015 U6 - http://dx.doi.org/10.1002/stco.201510029 SN - 1867-0539 N1 - The 13th Nordic Steel Construction Conference, Tampere, 2015 (NSCC-2015) VL - 8 IS - 3 SP - 194 EP - 200 PB - Ernst & Sohn CY - Berlin ER - TY - JOUR A1 - Oertel, Mario A1 - Bung, Daniel B. T1 - Stability and scour development of bed material on crossbar block ramps JF - International journal of sediment research N2 - Block ramps are ecologically oriented drop structures with adequate energy dissipation and partially moderate flow velocities. A special case is given with crossbar block ramps, where the upstream and downstream level difference is reduced by a series of basins. To prevent the total structure from failing, the stability of single boulders within the crossbars and the bed material in between must be guaranteed. The present paper addresses the stability of bed material and scour development for various flow regimes. Any bed material erosion may affect the stability of the crossbar boulders, which in turn can result in major damages of the ramp. Therefore new design approaches are developed to choose an appropriate bed material size and to avoid failures of crossbar block ramp structures. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.ijsrc.2014.12.003 SN - 1001-6279 VL - 30 IS - 4 SP - 344 EP - 350 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bayon, Arnau A1 - Valero, Daniel A1 - Garcia-Bartual, Rafael A1 - Vallés-Morán, Francisco José A1 - López-Jiménez, P. Amparo T1 - Performance assessment of OpenFOAM and FLOW-3D in the numerical modeling of a low Reynolds number hydraulic jump JF - Environmental Modelling & Software N2 - A comparative performance analysis of the CFD platforms OpenFOAM and FLOW-3D is presented, focusing on a 3D swirling turbulent flow: a steady hydraulic jump at low Reynolds number. Turbulence is treated using RANS approach RNG k-ε. A Volume Of Fluid (VOF) method is used to track the air–water interface, consequently aeration is modeled using an Eulerian–Eulerian approach. Structured meshes of cubic elements are used to discretize the channel geometry. The numerical model accuracy is assessed comparing representative hydraulic jump variables (sequent depth ratio, roller length, mean velocity profiles, velocity decay or free surface profile) to experimental data. The model results are also compared to previous studies to broaden the result validation. Both codes reproduced the phenomenon under study concurring with experimental data, although special care must be taken when swirling flows occur. Both models can be used to reproduce the hydraulic performance of energy dissipation structures at low Reynolds numbers. Y1 - 2016 SN - 1364-8152 U6 - http://dx.doi.org/10.1016/j.envsoft.2016.02.018 VL - 80 SP - 322 EP - 335 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. T1 - Sensitivity of turbulent Schmidt number and turbulence model to simulations of jets in crossflow JF - Environmental Modelling and Software N2 - Environmental discharges have been traditionally designed by means of cost-intensive and time-consuming experimental studies. Some extensively validated models based on an integral approach have been often employed for water quality problems, as recommended by USEPA (i.e.: CORMIX). In this study, FLOW-3D is employed for a full 3D RANS modelling of two turbulent jet-to-crossflow cases, including free surface jet impingement. Results are compared to both physical modelling and CORMIX to better assess model performance. Turbulence measurements have been collected for a better understanding of turbulent diffusion's parameter sensitivity. Although both studied models are generally able to reproduce jet trajectory, jet separation downstream of the impingement has been reproduced only by RANS modelling. Additionally, concentrations are better reproduced by FLOW-3D when the proper turbulent Schmidt number is used. This study provides a recommendation on the selection of the turbulence model and the turbulent Schmidt number for future outfall structures design studies. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.envsoft.2016.04.030 SN - 1364-8152 (electronic) VL - 82 SP - 218 EP - 228 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. T1 - Development of the interfacial air layer in the non-aerated region of high-velocity spillway flows: Instabilities growth, entrapped air and influence on the self-aeration onset JF - International Journal of Multiphase Flow N2 - Self-aeration is traditionally explained by the water turbulent boundary layer outer edge intersection with the free surface. This paper presents a discussion on the commonly accepted hypothesis behind the computation of the critical point of self-aeration in spillway flows and a new formulation is proposed based on the existence of a developing air flow over the free surface. Upstream of the inception point of self-aeration, some surface roughening has been often reported in previous studies which consequently implies some entrapped air transport and air–water flows coupling. Such air flow is proven in this study by presenting measured air velocities and computing the air boundary layer thickness for a 1V:2H smooth chute flow. Additionally, the growth rate of free surface waves has been analysed by means of Ultrasonic Sensors measurements, obtaining also the entrapped air concentration. High-speed camera imaging has been used for qualitative study of the flow perturbations. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.ijmultiphaseflow.2016.04.012 SN - 0301-9322 VL - 84 SP - 66 EP - 74 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bung, Daniel B. A1 - Valero, Daniel T1 - Optical flow estimation in aerated flows JF - Journal of Hydraulic Research N2 - Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150. Y1 - 2016 U6 - http://dx.doi.org/10.1080/00221686.2016.1173600 VL - 54 IS - 5 SP - 575 EP - 580 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Lopes, Pedro A1 - Leandro, Jorge A1 - Carvalho, Rita F. A1 - Bung, Daniel B. T1 - Alternating skimming flow over a stepped spillway JF - Environmental Fluid Mechanics Y1 - 2017 U6 - http://dx.doi.org/10.1007/s10652-016-9484-x SN - 1573-1510 VL - 17 IS - 2 SP - 303 EP - 322 PB - Springer CY - Berlin ER - TY - JOUR A1 - Höttges, Jörg T1 - QKan - Management of drainage system data with QGIS JF - Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings Y1 - 2017 VL - 17 IS - Article 13 SP - 95 EP - 100 ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. T1 - Artificial Neural Networks and pattern recognition for air-water flow velocity estimation using a single-tip optical fibre probe JF - Journal of Hydro-environment Research Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.jher.2017.08.004 SN - 1570-6443 VL - 19 IS - 3 SP - 150 EP - 159 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kerpen, Nils B. A1 - Bung, Daniel B. A1 - Valero, Daniel A1 - Schlurmann, Torsten T1 - Energy dissipation within the wave run-up at stepped revetments JF - Journal of Ocean University of China Y1 - 2017 U6 - http://dx.doi.org/10.1007/s11802-017-3355-z SN - 1993-5021 VL - 16 IS - 4 SP - 649 EP - 654 PB - Springer CY - Berlin ER - TY - JOUR A1 - Wolisz, Henryk A1 - Schütz, Thomas A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Kohrn, Markus A1 - Wesseling, Mark A1 - Müller, Dirk T1 - Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets JF - Energy Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.energy.2017.06.025 VL - 137 SP - 715 EP - 728 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. T1 - Reformulating self-aeration in hydraulic structures: Turbulent growth of free surface perturbations leading to air entrainment JF - International Journal of Multiphase Flow N2 - 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. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.ijmultiphaseflow.2017.12.011 SN - 0301-9322 VL - 100 SP - 127 EP - 142 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. T1 - Vectrino profiler spatial filtering for shear flows based on the mean velocity gradient equation JF - Journal of Hydraulic Engineering N2 - A new methodology is proposed to spatially filter acoustic Doppler velocimetry data from a Vectrino profiler based on the differential mean velocity equation. Lower and upper bounds are formulated in terms of physically based flow constraints. Practical implementation is discussed, and its application is tested against data gathered from an open-channel flow over a stepped macroroughness surface. The method has proven to detect outliers occurring all over the distance range sampled by the Vectrino profiler and has shown to remain applicable out of the region of validity of the velocity gradient equation. Finally, a statistical analysis suggests that physically obtained bounds are asymptotically representative. Y1 - 2018 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001485 SN - 0733-9429 N1 - Article number 04018037 VL - 144 IS - 7 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Crookston, B.M. T1 - Energy dissipation of a Type III basin under design and adverse conditions for stepped and smooth spillways JF - Journal of Hydraulic Engineering N2 - 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. Y1 - 2018 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001482 SN - 0733-9429 N1 - Article number 04018036 VL - 144 IS - 7 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Zhang, G. A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Chanson, H. T1 - On the estimation of free-surface turbulence using ultrasonic sensors JF - Flow Measurement and Instrumentation N2 - 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. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.flowmeasinst.2018.02.009 SN - 0955-5986 VL - 60 SP - 171 EP - 184 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bung, Daniel B. A1 - Valero, Daniel T1 - Re-aeration on stepped spillways with special consideration of entrained and entrapped air JF - Geosciences N2 - 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. Y1 - 2018 SN - 2076-3263 VL - 8 IS - 9 SP - Article number 333 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kramer, Matthias A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Towards reliable turbulence estimations with phase-detection probes: an adaptive window cross-correlation technique JF - Experiments in Fluids Y1 - 2019 U6 - http://dx.doi.org/10.1007/s00348-018-2650-9 SN - 1432-1114 VL - 60 EP - Article number 2 PB - Springer CY - Berlin ER - TY - JOUR A1 - Valero, Daniel A1 - Viti, Nicolo A1 - Gualtieri, Carlo T1 - Numerical Simulation of Hydraulic Jumps. Part 1: Experimental Data for Modelling Performance Assessment JF - Water Y1 - 2019 U6 - http://dx.doi.org/10.3390/w11010036 SN - 2073-4441 VL - 11 IS - 1 SP - Art. Nr. 36 PB - MDPI CY - Basel ER - TY - JOUR A1 - Viti, Nicolo A1 - Valero, Daniel A1 - Gualtieri, Carlo T1 - Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook JF - Water Y1 - 2019 U6 - http://dx.doi.org/10.3390/w11010028 SN - 2073-4441 VL - 11 IS - 1 SP - Art. Nr. 28 ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Robust estimators for turbulence properties assessment Y1 - 2019 SP - 1 EP - 24 ER - TY - JOUR A1 - Valero, D. A1 - Bung, Daniel B. A1 - Crookston, B. M. T1 - Closure to “Energy Dissipation of a Type III Basin under Design and Adverse Conditions for Stepped and Smooth Spillways” JF - Journal of Hydraulic Engineering Y1 - 2019 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001669 VL - 146 IS - 2 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel B. T1 - Robust estimators for free surface turbulence characterization: A stepped spillway application JF - Flow Measurement and Instrumentation N2 - Robust estimators are parameters insensitive to the presence of outliers. However, they presume the shape of the variables’ probability density function. This study exemplifies the sensitivity of turbulent quantities to the use of classic and robust estimators and the presence of outliers in turbulent flow depth time series. A wide range of turbulence quantities was analysed based upon a stepped spillway case study, using flow depths sampled with Acoustic Displacement Meters as the flow variable of interest. The studied parameters include: the expected free surface level, the expected fluctuation intensity, the depth skewness, the autocorrelation timescales, the vertical velocity fluctuation intensity, the perturbations celerity and the one-dimensional free surface turbulence spectrum. Three levels of filtering were utilised prior to applying classic and robust estimators, showing that comparable robustness can be obtained either using classic estimators together with an intermediate filtering technique or using robust estimators instead, without any filtering technique. Y1 - 2020 U6 - http://dx.doi.org/10.1016/j.flowmeasinst.2020.101809 SN - 0955-5986 VL - 76 IS - Art. 101809 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kuhnhenne, Markus A1 - Reger, Vitali A1 - Pyschny, Dominik A1 - Döring, Bernd T1 - Influence of airtightness of steel sandwich panel joints on heat losses JF - E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020) N2 - 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. Y1 - 2020 U6 - http://dx.doi.org/10.1051/e3sconf/202017205008 VL - 172 IS - Art. 05008 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Kerres, Karsten A1 - Gredigk-Hoffmann, Sylvia A1 - Jathe, Rüdiger A1 - Orlik, Stefan A1 - Sariyildiz, Mustafa A1 - Schmidt, Torsten A1 - Sympher, Klaus-Jochen A1 - Uhlenbroch, Adrian T1 - Future approaches for sewer system condition assessment JF - Water Practice & Technology N2 - 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. Y1 - 2020 U6 - http://dx.doi.org/10.2166/wpt.2020.027 SN - 1751-231X IS - 15 (2) SP - 386 EP - 393 PB - IWA Publishing CY - London ER - TY - JOUR A1 - Bung, Daniel B. A1 - Crookston, Brian M. A1 - Valero, Daniel T1 - Turbulent free-surface monitoring with an RGB-D sensor: the hydraulic jump case JF - Journal of Hydraulic Research Y1 - 2020 U6 - http://dx.doi.org/10.1080/00221686.2020.1844810 SN - 1814-2079 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Bung, Daniel Bernhard A1 - Erpicum, Sébastien A1 - Tullis, Blanke P. T1 - Advances in hydraulic structures engineering JF - Journal of Hydraulic Engineering Y1 - 2020 U6 - http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001851 SN - 0733-9429 (Druckausgabe) SN - 1943-7900 (Online-Ausgabe) VL - 147 IS - 1 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Döring, Bernd A1 - Göttsche, Joachim A1 - Reger, Vitali A1 - Kuhnhenne, Markus T1 - Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates JF - Geothermal Energy N2 - 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 Hellström’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. Y1 - 2021 U6 - http://dx.doi.org/10.1186/s40517-021-00201-3 SN - 2195-9706 N1 - Corresponding author: Tobias Blanke VL - 9 IS - Article number: 19 PB - Springer CY - Berlin ER - TY - JOUR A1 - Hagenkamp, Markus A1 - Blanke, Tobias A1 - Döring, Bernd T1 - Thermoelectric building temperature control: a potential assessment JF - International Journal of Energy and Environmental Engineering N2 - This study focuses on thermoelectric elements (TEE) as an alternative for room temperature control. TEE are semi-conductor devices that can provide heating and cooling via a heat pump effect without direct noise emissions and no refrigerant use. An efficiency evaluation of the optimal operating mode is carried out for different numbers of TEE, ambient temperatures, and heating loads. The influence of an additional heat recovery unit on system efficiency and an unevenly distributed heating demand are examined. The results show that TEE can provide heat at a coefficient of performance (COP) greater than one especially for small heating demands and high ambient temperatures. The efficiency increases with the number of elements in the system and is subject to economies of scale. The best COP exceeds six at optimal operating conditions. An additional heat recovery unit proves beneficial for low ambient temperatures and systems with few TEE. It makes COPs above one possible at ambient temperatures below 0 ∘C. The effect increases efficiency by maximal 0.81 (from 1.90 to 2.71) at ambient temperature 5 K below room temperature and heating demand Q˙h=100W but is subject to diseconomies of scale. Thermoelectric technology is a valuable option for electricity-based heat supply and can provide cooling and ventilation functions. A careful system design as well as an additional heat recovery unit significantly benefits the performance. This makes TEE superior to direct current heating systems and competitive to heat pumps for small scale applications with focus on avoiding noise and harmful refrigerants. Y1 - 2021 U6 - http://dx.doi.org/10.1007/s40095-021-00424-x N1 - Corresponding author: Markus Hagenkamp VL - 13 SP - 241 EP - 254 PB - Springer CY - Berlin ER - TY - JOUR A1 - Erpicum, Sebastien A1 - Crookston, Brian M. A1 - Bombardelli, Fabian A1 - Bung, Daniel B. A1 - Felder, Stefan A1 - Mulligan, Sean A1 - Oertel, Mario A1 - Palermo, Michele T1 - Hydraulic structures engineering: An evolving science in a changing world JF - Wires Water Y1 - 2021 U6 - http://dx.doi.org/10.1002/wat2.1505 SN - 2049-1948 VL - 8 IS - 2 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Valero, Daniel A1 - Schalko, Isabella A1 - Friedrich, Heide A1 - Abad, Jorge D. A1 - Bung, Daniel B. A1 - Donchyts, Gennadii A1 - Felder, Stefan A1 - Ferreira, Rui M. L. A1 - Hohermuth, Benjamin A1 - Kramer, Matthias A1 - Li, Danxun A1 - Mendes, Luis A1 - Moreno-Rodenas, Antonio A1 - Nones, Michael A1 - Paron, Paolo A1 - Ruiz-Villanueva, Virginia A1 - Wang, Ruo-Qian A1 - Franca, Mario J. T1 - Pathways towards democratization of hydro-environment observations and data JF - Iahr White Paper Series Y1 - 2021 IS - 1 SP - 1 EP - 9 PB - International Association for Hydro-Environment Engineering and Research (IAHR) ER - TY - JOUR A1 - Cheenakula, Dheeraja A1 - Hoffstadt, Kevin A1 - Krafft, Simone A1 - Reinecke, Diana A1 - Klose, Holger A1 - Kuperjans, Isabel A1 - Grömping, Markus T1 - Anaerobic digestion of algal–bacterial biomass of an Algal Turf Scrubber system JF - Biomass Conversion and Biorefinery N2 - 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. KW - Biogas KW - Methane KW - Algal Turf Scrubber KW - Algal–bacterial bioflm KW - Circular bioeconomy Y1 - 2022 U6 - http://dx.doi.org/10.1007/s13399-022-03236-z SN - 2190-6823 N1 - Corresponding author: Dheeraja Cheenakula VL - 13 SP - 15 Seiten PB - Springer CY - Berlin ER - TY - JOUR A1 - Valero, Daniel A1 - Bung, Daniel B. A1 - Erpicum, Sebastien A1 - Peltier, Yann A1 - Dewals, Benjamin T1 - Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling JF - Journal of Hydro-environment Research N2 - Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models). KW - coherent structures KW - hydraulic modelling KW - model performance KW - Proper Orthogonal Decomposition KW - Q-criterion Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.jher.2022.03.002 SN - 1570-6443 IS - In Press PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - von Häfen, Hajo A1 - Krautwald, Clemens A1 - Stolle, Jacob A1 - Bung, Daniel Bernhard A1 - Goseberg, Nils T1 - Overland flow of broken solitary waves over a two-dimensional coastal plane JF - Coastal Engineering N2 - 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. KW - Landslide tsunamis KW - Hazard assessment KW - Large scale tests KW - Overland flow KW - Solitary waves Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.coastaleng.2022.104125 SN - 1872-7379 VL - 175 IS - August PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cheenakula, Dheeraja A1 - Griebel, Kai A1 - Montag, David A1 - Grömping, Markus ED - Huang, Xiaowu T1 - Concept development of a mainstream deammonification and comparison with conventional process in terms of energy, performance and economical construction perspectives JF - Frontiers in Microbiology N2 - 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. KW - anammox KW - energy efficiency KW - mainstream deammonification KW - nitrogen elimination KW - wastewater Y1 - 2023 U6 - http://dx.doi.org/10.3389/fmicb.2023.1155235 SN - 1664-302X VL - 14 IS - 11155235 SP - 1 EP - 15 PB - Frontiers ER - TY - JOUR A1 - Cheenakula, Dheeraja A1 - Paulsen, Svea A1 - Ott, Fabian A1 - Grömping, Markus T1 - Operational window of a deammonifying sludge for mainstream application in a municipal wastewater treatment plant JF - Water and Environment Journal N2 - 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. KW - Anammox KW - Mainstream KW - Nitrogen removal KW - Partial nitritation KW - Wastewater Y1 - 2023 U6 - http://dx.doi.org/10.1111/wej.12898 SN - 1747-6593 N1 - Corresponding author: Dheeraja Cheenakula IS - Early View SP - 1 EP - 12 PB - Wiley CY - Chichester ER -