Browsing by Author "Cienfuegos, R."

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    A fourth-order compact finite volume scheme for fully nonlinear and weakly dispersive Boussinesq-type equations. Part II: Boundary conditions and validation
    (WILEY, 2007) Cienfuegos, R.; Barthelemy, E.; Bonneton, P.
    This paper supplements the validation of the fourth-order compact finite volume Boussinesq-type model presented by Cienfuegos et al. (Int. J. Numer. Meth. Fluids 2006, in press). We discuss several issues related to the application of the model for realistic wave propagation problems where boundary conditions and uneven bathymetries must be considered. We implement a moving shoreline boundary condition following the lines given by Lynett et al. (Coastal Eng. 2002; 46:89-107), while an absorbing-generating seaward boundary and an impermeable vertical wall boundary are approximated using a characteristic decomposition of the Serre equations. Using several benchmark tests, both numerical and experimental, we show that the new finite volume model is able to correctly describe nonlinear wave processes from shallow waters and up to wavelengths which correspond to the theoretical deep water limit. The results compare favourably with those reported using former fully nonlinear and weakly dispersive Boussinesq-type solvers even when time integration is conducted with Courant numbers greater than 1.0. Furthermore, excellent nonlinear performance is observed when numerical computations are compared with several experimental tests on solitary waves shoaling over planar beaches up to breaking. A preliminary test including the wave-breaking parameterization described by Cienfuegos (Fifth International Symposium on Ocean Wave Measurement Analysis, Madrid, Spain, 2005) shows that the Boussinesq model can be extended to deal with surf zone waves. Finally, practical aspects related to the application of a high-order implicit filter as given by Gaitonde et al. (Int. J. Numer Methods Engng 1999; 45:1849-1869) to damp out unphysical wavelengths, and the numerical robustness of the finite volume scheme are also discussed. Copyright (c) 2006 John Wiley & Sons, Ltd.
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    Energy Dissipation and Turbulent Production in Weak Hydraulic Jumps
    (ASCE-AMER SOC CIVIL ENGINEERS, 2010) Mignot, E.; Cienfuegos, R.
    The present experimental investigation focuses on energy dissipation and turbulence production in two undeveloped and a partially developed inflow weak hydraulic jumps, measured with micro-ADVs. For the undeveloped inflow jumps, the turbulence production is mostly confined in the shear layer located in the upper part of the water column. For the partially developed inflow jump, two peak turbulence production regions are observed, one in the upper shear layer and the second in the near-wall region. Moreover, the measured energy dissipation distribution in the jumps reveals a similar longitudinal decay of energy dissipation integrated over the flow sections and of maximum turbulence production values from the intermediate jump region toward its downstream section.
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    Impact of earthquake magnitude on the estimation of tsunami evacuation casualties
    (2018) Castro, S.; Poulos, A.; Urrutia, A.; Herrera, J. C.; Cienfuegos, R.; Llera Martin, Juan Carlos de la
    The importance of evacuation plans has been widely proven in recent tsunami events. Several evacuation models have been proposed to develop these plans and estimate city evacuation times. Typically, single extreme earthquake scenarios are used in these estimations; however, the impact of earthquake damage on the evacuation routes is usually neglected in these models. This article deals with the evaluation of the effect of three different earthquake magnitudes and the following tsunamis. Several spectral accelerations were sampled for each magnitude to estimate city damage, and from there the reduced capacity of evacuation routes due to earthquake debris. An agent-based evacuation model was used to assess the evacuation times for the city of Iquique, located in north Chile. Results show significant variability for different magnitude scenarios, thus leading to an observed increment on evacuation times up to 40% and an increase in the number of casualties due to the evacuation delay caused by earthquake debris spread on the evacuation routes
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    Integrating Fluorescent Dye Flow-Curve Testing and Acoustic Doppler Velocimetry Profiling for In Situ Hydraulic Evaluation and Improvement of Clarifier Performance
    (WILEY, 2010) Tarud, F.; Aybar, M.; Pizarro, G.; Cienfuegos, R.; Pasten, P.
    Enhancing the performance of clarifiers requires a thorough understanding of their hydraulics. Fluorescence spectroscopy and acoustic doppler velocimeter (ADV) profiling generally have been used separately to evaluate secondary settlers. We propose that simultaneous use of these techniques is needed to obtain a more reliable and useful evaluation. Experiments were performed on laboratory- and full-scale clarifiers. Factors affecting Fluorescein and Rhodamine 6G properties were identified. Underestimations up to 500% in fluorescence intensities may be derived from differential fluorescence quenching by oxygen. A careful control and interpretation of fluorescent dye experiments is needed to minimize artifacts in real settings. While flow-curve tests constructed under controlled conditions provided a more accurate overall quantitative estimation of the hydraulic performance, ADV velocity and turbulence profiling provided a detailed spatial understanding of flow patterns that was used to troubleshoot and fix the causes of hydraulic short-circuits. Water Environ. Res., 82, 675 (2010).
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    Kinematics of waves propagating and breaking on a barred beach
    (GAUTHIER-VILLARS/EDITIONS ELSEVIER, 2011) Michallet, H.; Cienfuegos, R.; Barthelemy, E.; Grasso, F.
    Laboratory experiments are conducted in a wave facility with a loose sediment beach in order to estimate the wave characteristics needed for sediment transport modeling. A roller model and a Boussinesq-type model are used for comparing and discussing the experimental results. It is shown that the velocity skewness and acceleration skewness evolutions along the beach profile can be estimated from measurements of surface elevations. The roller model correctly reproduces the set-up and undertow measurements as long as the cross-shore variations of the second-order moment of the free surface displacement are taken into account. The Boussinesq model correctly reproduces the wave non-linearities with some discrepancies in the breaking region over the bar topography. (C) 2011 Elsevier Masson SAS. All rights reserved.
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    Recent advances in Serre-Green Naghdi modelling for wave transformation, breaking and runup processes
    (ELSEVIER, 2011) Bonneton, P.; Barthelemy, E.; Chazel, F.; Cienfuegos, R.; Lannes, D.; Marche, F.; Tissier, M.
    To describe the strongly nonlinear dynamics of waves propagating in the final stages of shoaling and in the surf and swash zones, fully nonlinear models are required. The ability of the Serre or Green Naghdi (S-GN) equations to reproduce this nonlinear processes is reviewed. Two high-order methods for solving S-GN equations, based on Finite Volume approaches, are presented. The first one is based on a quasi-conservative form of the S-GN equations, and the second on a hybrid Finite Volume/Finite Difference method. We show the ability of these two approaches to accurately simulate nonlinear shoaling, breaking and runup processes. (C) 2011 Elsevier Masson SAS. All rights reserved.
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    River mouths and coastal lagoons in central Chile
    (2017) Cienfuegos, R.; Campino, J.R.; Gironas Leon, Jorge Alfredo; Almar, R.; Villagrán, M.