@article{HoettgesArnoldRouve1994,
  author    = {H{\"o}ttges, J{\"o}rg and Arnold, Uwe and Rouv{\´e}, Gerhard},
  title     = {Measurement of transverse mixing using digital image acquisition},
  series = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven},
  journal   = {Mixing and transport in the environment : a memorial volume for Catherine M. Allen (1954-1991) / ed. by Keith J. Beven},
  publisher = {Wiley},
  address   = {Chichester [u.a.]},
  isbn      = {0471941425},
  pages     = {XVI, 458 S., [8] Bl : Ill. (z.T. farb.), graph. Da},
  year      = {1994},
  language  = {en}
}
@article{LeandroBungCarvalho2014,
  author    = {Leandro, J. and Bung, Daniel B. and Carvalho, R.},
  title     = {Measuring void fraction and velocity fields of a stepped spillway for skimming flow using non-intrusive methods},
  series = {Experiments in fluids},
  journal   = {Experiments in fluids},
  number    = {55},
  publisher = {Springer Nature},
  address   = {Heidelberg},
  issn      = {0723-4864 (Print) ; 1432-1114 (Online)},
  doi       = {10.1007/s00348-014-1732-6},
  pages     = {Art. 1732},
  year      = {2014},
  language  = {en}
}
@article{BlankeHagenkampDoeringetal.2021,
  author    = {Blanke, Tobias and Hagenkamp, Markus and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Reger, Vitali and Kuhnhenne, Markus},
  title     = {Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates},
  series = {Geothermal Energy},
  volume    = {9},
  journal   = {Geothermal Energy},
  number    = {Article number: 19},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2195-9706},
  doi       = {10.1186/s40517-021-00201-3},
  pages     = {23 Seiten},
  year      = {2021},
  abstract  = {Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellstr{\"o}m's borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54\% of the outer pipe radius for laminar fow and 60\% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth's thermal properties and the fow type. Conclusively, coaxial geothermal probes' design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.},
  language  = {en}
}
@article{BienerSasseArnoldetal.1999,
  author    = {Biener, Ernst and Sasse, T. and Arnold, J. and Woltering, S.},
  title     = {New treatment of harbour sludge in Bremen and Bremerhaven / E. Biener ; T. Sasse ; J. Arnold ; S. Woltering ; N. Binder},
  series = {Characterisation and treatment of sediments : Antwerpen, Belgium, September 15 - 17, 1999 ; [preceded by 12th International Harbour Congress] ; proceedings / CATS 4. Ed.: G. De Schutter. Organized by: Technologisch Instituut, Koninklijke Vlaamse Ingenieursvereniging},
  journal   = {Characterisation and treatment of sediments : Antwerpen, Belgium, September 15 - 17, 1999 ; [preceded by 12th International Harbour Congress] ; proceedings / CATS 4. Ed.: G. De Schutter. Organized by: Technologisch Instituut, Koninklijke Vlaamse Ingenieursvereniging},
  publisher = {Technolog. Inst.},
  address   = {Anvers},
  isbn      = {9076019118},
  pages     = {115 -- 122},
  year      = {1999},
  language  = {en}
}
@article{Bung2013,
  author    = {Bung, Daniel B.},
  title     = {Non-intrusive detection of air-water surface roughness in self-aerated chute flows},
  series = {Journal of hydraulic research},
  volume    = {Vol. 51},
  journal   = {Journal of hydraulic research},
  number    = {Iss. 3},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {1814-2079 (E-Journal); 0022-1686 (Print)},
  pages     = {322 -- 329},
  year      = {2013},
  language  = {en}
}
@article{ValeroVitiGualtieri2019,
  author    = {Valero, Daniel and Viti, Nicolo and Gualtieri, Carlo},
  title     = {Numerical Simulation of Hydraulic Jumps. Part 1: Experimental Data for Modelling Performance Assessment},
  series = {Water},
  volume    = {11},
  journal   = {Water},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4441},
  doi       = {10.3390/w11010036},
  pages     = {Art. Nr. 36},
  year      = {2019},
  language  = {en}
}
@article{VitiValeroGualtieri2019,
  author    = {Viti, Nicolo and Valero, Daniel and Gualtieri, Carlo},
  title     = {Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook},
  series = {Water},
  volume    = {11},
  journal   = {Water},
  number    = {1},
  issn      = {2073-4441},
  doi       = {10.3390/w11010028},
  pages     = {Art. Nr. 28},
  year      = {2019},
  language  = {en}
}
@article{ZhangValeroBungetal.2018,
  author    = {Zhang, G. and Valero, Daniel and Bung, Daniel B. and Chanson, H.},
  title     = {On the estimation of free-surface turbulence using ultrasonic sensors},
  series = {Flow Measurement and Instrumentation},
  volume    = {60},
  journal   = {Flow Measurement and Instrumentation},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0955-5986},
  doi       = {10.1016/j.flowmeasinst.2018.02.009},
  pages     = {171 -- 184},
  year      = {2018},
  abstract  = {Accurate determination of free-surface dynamics has attracted much research attention during the past decade and has important applications in many environmental and water related areas. In this study, the free-surface dynamics in several turbulent flows commonly found in nature were investigated using a synchronised setup consisting of an ultrasonic sensor and a high-speed video camera. Basic sensor capabilities were examined in dry conditions to allow for a better characterisation of the present sensor model. The ultrasonic sensor was found to adequately reproduce free-surface dynamics up to the second order, especially in two-dimensional scenarios with the most energetic modes in the low frequency range. The sensor frequency response was satisfactory in the sub-20 Hz band, and its signal quality may be further improved by low-pass filtering prior to digitisation. The application of the USS to characterise entrapped air in high-velocity flows is also discussed.},
  language  = {en}
}
@article{CheenakulaPaulsenOttetal.2023,
  author    = {Cheenakula, Dheeraja and Paulsen, Svea and Ott, Fabian and Gr{\"o}mping, Markus},
  title     = {Operational window of a deammonifying sludge for mainstream application in a municipal wastewater treatment plant},
  series = {Water and Environment Journal},
  journal   = {Water and Environment Journal},
  number    = {Early View},
  publisher = {Wiley},
  address   = {Chichester},
  issn      = {1747-6593},
  doi       = {10.1111/wej.12898},
  pages     = {1 -- 12},
  year      = {2023},
  abstract  = {The present work aimed to study the mainstream feasibility of the deammonifying sludge of side stream of municipal wastewater treatment plant (MWWTP) in Kaster, Germany. For this purpose, the deammonifying sludge available at the side stream was investigated for nitrogen (N) removal with respect to the operational factors temperature (15-30°C), pH value (6.0-8.0) and chemical oxygen demand (COD)/N ratio (≤1.5-6.0). The highest and lowest N-removal rates of 0.13 and 0.045 kg/(m³ d) are achieved at 30 and 15°C, respectively. Different conditions of pH and COD/N ratios in the SBRs of Partial nitritation/anammox (PN/A) significantly influenced both the metabolic processes and associated N-removal rates. The scientific insights gained from the current work signifies the possibility of mainstream PN/A at WWTPs. The current study forms a solid basis of operational window for the upcoming semi-technical trails to be conducted prior to the full-scale mainstream PN/A at WWTP Kaster and WWTPs globally.},
  language  = {en}
}
@article{BungValero2016,
  author    = {Bung, Daniel B. and Valero, Daniel},
  title     = {Optical flow estimation in aerated flows},
  series = {Journal of Hydraulic Research},
  volume    = {54},
  journal   = {Journal of Hydraulic Research},
  number    = {5},
  publisher = {Taylor \& Francis},
  address   = {London},
  doi       = {10.1080/00221686.2016.1173600},
  pages     = {575 -- 580},
  year      = {2016},
  abstract  = {Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn-Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn-Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.},
  language  = {en}
}