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  - 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  - 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  - 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, 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  -