@inproceedings{ValeroVogelSchmidtetal.2018,
  author    = {Valero, Daniel and Vogel, Jochen and Schmidt, Daniel and Bung, Daniel Bernhard},
  title     = {Three-dimensional flow structure inside the cavity of a non-aerated stepped chute},
  series = {7th IAHR International Symposium on Hydraulic Structures, Aachen, Germany, 15-18 May},
  booktitle = {7th IAHR International Symposium on Hydraulic Structures, Aachen, Germany, 15-18 May},
  isbn      = {978-0-692-13277-7},
  doi       = {10.15142/T3GH17},
  pages     = {12 Seiten},
  year      = {2018},
  language  = {en}
}
@article{ZhangValeroBungetal.2018,
  author    = {Zhang, G. and Valero, Daniel and Bung, Daniel Bernhard 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}
}
@inproceedings{BungValero2017,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {FlowCV - An open-source toolbox for computer vision applications in turbulent flows},
  series = {Proceedings of the 37th IAHR World Congress August 13 - 18, 2017, Kuala Lumpur, Malaysia},
  booktitle = {Proceedings of the 37th IAHR World Congress August 13 - 18, 2017, Kuala Lumpur, Malaysia},
  issn      = {2521-716X},
  pages     = {5356 -- 5365},
  year      = {2017},
  language  = {en}
}
@article{ValeroChansonBung2019,
  author    = {Valero, Daniel and Chanson, Hubert and Bung, Daniel Bernhard},
  title     = {Robust estimators for turbulence properties assessment},
  pages     = {1 -- 24},
  year      = {2019},
  language  = {en}
}
@article{KerpenBungValeroetal.2017,
  author    = {Kerpen, Nils B. and Bung, Daniel Bernhard and Valero, Daniel and Schlurmann, Torsten},
  title     = {Energy dissipation within the wave run-up at stepped revetments},
  series = {Journal of Ocean University of China},
  volume    = {16},
  journal   = {Journal of Ocean University of China},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1993-5021},
  doi       = {10.1007/s11802-017-3355-z},
  pages     = {649 -- 654},
  year      = {2017},
  language  = {en}
}
@article{ValeroBung2016,
  author    = {Valero, Daniel and Bung, Daniel Bernhard},
  title     = {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},
  series = {International Journal of Multiphase Flow},
  volume    = {84},
  journal   = {International Journal of Multiphase Flow},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9322},
  doi       = {10.1016/j.ijmultiphaseflow.2016.04.012},
  pages     = {66 -- 74},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@inproceedings{ValeroBungCrookstonetal.2016,
  author    = {Valero, Daniel and Bung, Daniel Bernhard and Crookston, B. M. and Matos, J.},
  title     = {Numerical investigation of USBR type III stilling basin performance downstream of smooth and stepped spillways},
  series = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  booktitle = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  editor    = {Crookston, B. and Tullis, B.},
  isbn      = {978-1-884575-75-4},
  doi       = {10.15142/T340628160853},
  pages     = {635 -- 646},
  year      = {2016},
  language  = {en}
}
@inproceedings{BungValero2016,
  author    = {Bung, Daniel Bernhard and Valero, Daniel},
  title     = {Application of the optical flow method to velocity determination in hydraulic structure models},
  series = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  booktitle = {Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June 2016},
  editor    = {Crookston, B. and Tullis, B.},
  isbn      = {978-1-884575-75-4},
  doi       = {10.15142/T3150628160853},
  pages     = {223 -- 232},
  year      = {2016},
  language  = {en}
}
@article{ValeroBung2018,
  author    = {Valero, Daniel and Bung, Daniel Bernhard},
  title     = {Reformulating self-aeration in hydraulic structures: Turbulent growth of free surface perturbations leading to air entrainment},
  series = {International Journal of Multiphase Flow},
  volume    = {100},
  journal   = {International Journal of Multiphase Flow},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0301-9322},
  doi       = {10.1016/j.ijmultiphaseflow.2017.12.011},
  pages     = {127 -- 142},
  year      = {2018},
  abstract  = {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.},
  language  = {en}
}
@article{ValeroBungErpicumetal.2022,
  author    = {Valero, Daniel and Bung, Daniel Bernhard and Erpicum, Sebastien and Peltier, Yann and Dewals, Benjamin},
  title     = {Unsteady shallow meandering flows in rectangular reservoirs: a modal analysis of URANS modelling},
  series = {Journal of Hydro-environment Research},
  journal   = {Journal of Hydro-environment Research},
  number    = {In Press},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1570-6443},
  doi       = {10.1016/j.jher.2022.03.002},
  year      = {2022},
  abstract  = {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).},
  language  = {en}
}