Browsing by Author "Cienfuegos, Rodrigo"

Now showing 1 - 12 of 12
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    A new breaking wave height direct estimator from video imagery
    (ELSEVIER SCIENCE BV, 2012) Almar, Rafael; Cienfuegos, Rodrigo; Catalan, Patricio A.; Michallet, Herve; Castelle, Bruno; Bonneton, Philippe; Marieu, Vincent
    Breaker height is a key parameter of nearshore processes and the demand for a continuous remote estimator is pressing. In this paper we present a standalone remote video-based method that estimates wave height at the breakpoint. Individual breaking events are first identified from changes in optical properties and wave height is further derived from the optical signature at the onset of breaking. An extended validation is performed using a dense wave basin dataset. The results show the ability of the method to measure individual breaker heights (9% of mean error, 18% RMS). In addition, the unique combination of in situ and remotely sensed data allows the estimation of two other breaking-related parameters, the height-to-depth ratio and wave front face slope, which show a substantial amount of dispersion. Because nearshore video systems are rapidly spreading over world coasts, this low-cost remote breaker height estimator should encounter large interest in coastal engineering studies. (C) 2011 Elsevier B.V. All rights reserved.
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    ASSESSMENT OF FAST SPECTRAL WAVE TRANSFER METHODOLOGIES FROM DEEP TO SHALLOW WATERS IN THE FRAMEWORK OF ENERGY RESOURCE QUANTIFICATION IN THE CHILEAN COAST
    (2014) Domínguez, Juan Carlos; Cienfuegos, Rodrigo; Catalán, Patricio; Zamorano, Luis; Lucero, Felipe
    Alternative wave transfer methodologies from deep to shallow water that aim at reducing the computational time in cases where the full propagation of a large number of wave climates is often prohibitive are defined and tested against full spectral propagation using complex measured wave climates. A proposed method is presented in this work which is able to accurately reproduce the shape transformation of directional spectra while significantly reducing the computational time. Another transfer method is also validated, which can achieve relatively good results when there is no spectral information and only statistical wave parameters (e.g. significant wave height, peak period and mean wave direction) are available. Finally, an application of the proposed method in the framework of energy resource quantification in Chile is presented.
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    Détection de courants marins côtiers à partir de séquences vidéo
    (2014) Larnier, Stanislas; Almar, Rafael; Cienfuegos, Rodrigo; Lejay, Antoine; Dhersin, Jean-Stéphane
    Les courants marins à proximité d’une côte contrôlent le transport de sédiment et son évolution. Or leur estimation par des instruments sur site est difficile et coûteuse. Les systèmes de télédétection reposant sur des observations constituent une alternative prometteuse lorsque la mousse dérivante laissée après le passage de vagues déferlantes est visible. Pourtant, seules quelques méthodes ont été proposées à ce jour dans la littérature.Dans cet article, nous décrivons deux nouvelles méthodes : l’une basée sur les images vidéos considérées dans leur globalité et l’autre basée sur des timestacks le long de la côte. La première approche est une extension de la méthode Particle Image Velocimetry (PIV). La seconde approche produit une estimation de la composante parallèle à la côte des courants de surface en utilisant la transformée de Radon sur des séries temporelles de données en une dimension. Cette dernière nécessite moins de données.Les vidéos utilisées dans cet article proviennent d’une campagne menée sur la zone de l’embouchure de Mataquito dans la région de Maule au Chili. Elles font partie d’une étude sur l’évolution côtière de la zone de Mataquito après le tsunami chilien de 2010. Une comparaison a été également réalisée avec les mesures d’un courantomètre prises lors de la campagne du Truc Vert de 2008 en Aquitaine, France. Elle a eu lieu lors d’une tempête qui a provoqué l’évolution d’une barre sableuse.
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    Ex post analysis of engineered tsunami mitigation measures in the town of Dichato, Chile
    (Springer, 2020) Oportus, Maximiliano; Cienfuegos, Rodrigo; Urrutia, Alejandro; Aránguiz, Rafael; Catalán, Patricio A; Hube, Matías A.; Centro Nacional de Investigación para la Gestión Integrada de Desastres Naturales (CIGIDEN)
    Due to Chile's notorious and frequent seismic activity, earthquake- and tsunami-related studies have become a priority in the interest of developing effective countermeasures to mitigate their impacts and to improve the country's resilience. Mitigation measures are key to accomplish these objectives. Therefore, this investigation adopts a tsunami damage assessment framework to evaluate the direct benefits of tsunami mitigation works implemented by the Chilean government in the town of Dichato in the aftermath of the 2010 tsunami. We perform an ex post analysis of the potential damage reduction produced by these works studying what would have been the consequences on the built environment if they were in place for the tsunami that hit this area after the Maule earthquake in February 27, 2010. We use state-of-the-art tsunami simulation models at high resolution to assess the reduction in tsunami intensity measures, which serve as input to evaluate the benefit from averted damage against the costs of the mitigation measures. The obtained results show a reduction in the flooded area and a delay in the arrival times for the first smaller tsunami waves, but a negligible damage reduction when confronted to the largest waves. In conclusion, the tsunami mitigation measures would not have been effective to reduce the impact of the tsunami generated by the Maule earthquake in the town of Dichato, but could have had a benefit in retarding the inundation of low-land areas for the first smaller tsunami waves. The latter suggests that these works might be useful to mitigate storm waves or tsunamis of much smaller scales than the one that hit central-south Chile in 2010.
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    Flood risk from geophysical and hydroclimatic hazards: an essential integration for disaster risk management and climate change adaptation in the coastal zone
    (2022) Cienfuegos, Rodrigo
    Coastal zones worldwide have been subjected to increasingly high anthropic pressures over the last 50 years. The rapid urban growth rate together with the acceleration of Climate Change are boosting negative impacts on a wide range of coastal socioecological systems around the globe: as exposure, vulnerability, and the frequency and intensity of hydroclimatic hazards increase, so does disaster risk. Controlling exposure is the most efficient way of reducing flood risk; to this end, urban and infrastructure engineering design and planning processes should work hand in hand. Nonetheless, defining the "acceptable" risk level is not a technical question; it requires evidence-based guidance from "experts", but sustainable solutions can only be reached through social negotiation processes conducted in the political arena. New forms of coastal governance should be devised.
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    From Multi-Risk Evaluation to Resilience Planning: The Case of Central Chilean Coastal Cities
    (2019) Barria, Pilar; Luisa Cruzat, Maria; Cienfuegos, Rodrigo; Gironas, Jorge; Escauriaza Mesa, Cristian Rodrigo; Bonilla, Carlos; Moris, Roberto; Ledezma, Christian; Guerra, Maricarmen; Rodriguez, Raimundo; Torres, Alma
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    Lagrangian drifter modelling of an experimental RIP current
    (2012) Suarez, Leandro; Cienfuegos, Rodrigo; Escauriaza, Cristian; Barthélemy, Eric; Michallet, Hervé
    A non-uniform alongshore wave forcing on an experimental uneven mobile bathymetry create mean circulation on a rip channel. A 2D numerical hydrodynamic model that integrates the non-linear shallow-water equations in a shock-capturing finite-volume framework is used to validate the nearshore circulation, and drifters displacement.
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    On the application of a Boussinesq model to river flows including shocks
    (ELSEVIER SCIENCE BV, 2009) Mignot, Emmanuel; Cienfuegos, Rodrigo
    SERR-1D is a 4th-order finite volume 1D Boussinesq model including wave breaking energy dissipation through extra diffusive-like terms. This model has been primarily conceived to compute wave propagation in coastal areas and has been validated for breaking and non-breaking waves propagating over uneven bathymetries (Cienfuegos et al., 2005, 2006a, b, 2007). The present paper aims at investigating the ability of SERR-1D to simulate challenging fluvial hydraulic applications such as sudden gate operation in open channels generating short waves, dam-break flows and a steady hydraulic jump over a bump. The performance of the absorbing-generating boundary condition implemented in SERR-1D is first analysed in the context of fluvial applications where relatively short waves must be evacuated from the computational domain without producing spurious reflection. Next, by comparing numerical results to analytical and experimental dam-break test cases we show that the model is able to reproduce the overall features of these flows, but that additional care should be paid to the representation of energy dissipation and front speed in order to accurately represent bore dynamics. (C) 2008 Elsevier B.V. All rights reserved.
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    Spatial evolution of turbulence characteristics in weak hydraulic jumps
    (TAYLOR & FRANCIS LTD, 2011) Mignot, Emmanuel; Cienfuegos, Rodrigo
    This experimental investigation focuses on the turbulence features of weak hydraulic jumps in rectangular channels for two different approach flow lengths. The turbulent kinetic energy equation includes the turbulence production and dissipation terms, two advection and two turbulent transport terms and the pressure transport term, which could not be measured, however. For jumps with a limited approach flow length, the turbulence production is mostly confined to the shear layer, while for jumps with a longer approach flow length, an additional peak turbulence production region is observed at the near-wall region due to boundary layer separation. The turbulent energy is then transported by the mean flow both towards the free surface and into the downstream direction and is diffused by turbulent processes away from the energetic shear layer towards less energetic regions. Dissipation occurs mostly in the shear layer along the upstream portion of the jump and over most of the flow depth further downstream.
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    The kinematics and stability of solitary and cnoidal wave solutions of the Serre equations
    (ELSEVIER, 2011) Carter, John D.; Cienfuegos, Rodrigo
    The Serre equations are a pair of strongly nonlinear, weakly dispersive, Boussinesq-type partial differential equations. They model the evolution of the surface elevation and the depth-averaged horizontal velocity of an inviscid, irrotational, incompressible, shallow fluid. They admit a three-parameter family of cnoidal wave solutions with improved kinematics when compared to KdV theory. We examine their linear stability and establish that waves with sufficiently small amplitude/steepness are stable while waves with sufficiently large amplitude/steepness are unstable. (C) 2010 Elsevier Masson SAS. All rights reserved.
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    Wave-Breaking Model for Boussinesq-Type Equations Including Roller Effects in the Mass Conservation Equation
    (ASCE-AMER SOC CIVIL ENGINEERS, 2010) Cienfuegos, Rodrigo; Barthelemy, Eric; Bonneton, Philippe
    We investigate the ability of a ID fully nonlinear Boussinesq model including breaking to reproduce surf zone waves in terms of wave height and nonlinear intraphase properties such as asymmetry and skewness. An alternative approach for wave-breaking parameterization including roller effects through diffusive-type terms on both, the mass conservation and momentum equations is developed and validated on regular wave and solitary wave experiments as an attempt to improve wave height and left-right asymmetry estimates. The new approach is able to reproduce wave height decay, and intraphase nonlinear properties within the entire surf zone of spilling breakers without requiring temporal evolution of model parameters.