TY  - JOUR
A1  - Valero, Daniel
A1  - Bung, Daniel Bernhard
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  - https://doi.org/10.1016/j.ijmultiphaseflow.2017.12.011
SN  - 0301-9322
VL  - 100
SP  - 127
EP  - 142
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - RPRT
A1  - Fischedick, Manfred
A1  - Schoof, René
A1  - Hebel, Christoph
A1  - Merkens, Torsten
T1  - Sektorenkopplung als Herausforderung und Chance für das Energieland NRW : Handlungsoptionen und Ergebnispapier der Expertengruppe AG 4 „Sektoren- kopplung“ im Netzwerk Netze und Speicher der EnergieAgentur.NRW im Auftrag des Landes Nordrhein-Westfalen / EnergieAgentur.NRW GmbH
Y1  - 2018
ER  - 
TY  - CHAP
A1  - Valero, Daniel
A1  - Vogel, Jochen
A1  - Schmidt, Daniel
A1  - Bung, Daniel Bernhard
T1  - Three-dimensional flow structure inside the cavity of a non-aerated stepped chute
T2  - 7th IAHR International Symposium on Hydraulic Structures, Aachen, Germany, 15-18 May
Y1  - 2018
SN  - 978-0-692-13277-7
U6  - https://doi.org/10.15142/T3GH17
ER  - 
TY  - CHAP
A1  - Duffner, Markus
A1  - Moorkamp, Wilfried
A1  - Peterson, Leif Arne
A1  - Uibel, Thomas
ED  - Kuhlmann, Ulrike
T1  - Untersuchungen zur Tragfähigkeit und Steifigkeit eines neuartigen Wandelements in Holzbauweisen
T2  - Doktorandenkolloquium Holzbau Forschung + Praxis : Stuttgart, 08./09. März 2018
Y1  - 2018
SP  - 131
EP  - 139
PB  - Universität Stuttgart, Institut für Konstruktion und Entwurf
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Valero, Daniel
A1  - Bung, Daniel Bernhard
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  - https://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  -