Browsing by Author "Cienfuegos, R."

Now showing 1 - 10 of 10
  • Thumbnail Image
    Item
    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.
  • No Thumbnail Available
    Item
    A fourth-order compact finite volume scheme for fully nonlinear and weakly dispersive Boussinesq-type equations.: Part I
    (2006) Cienfuegos, R.; Barthelemy, E.; Bonneton, P.
    A high-order finite volume scheme is developed to numerically integrate a fully nonlinear and weakly dispersive set of Boussinesq-type equations (the so-called Serre equations) (J. Fluid Mech. 1987; 176:117-134; Surveys Geophys. 2004; 25(3-4):315-337). The choice of this discretization strategy is motivated by the fact that this particular set of equations is recasted in a convenient quasi-conservative form. Cell face values are reconstructed using implicit compact schemes (J. Comput. Phys. 1999; 156:137-180; J. Comput. Phys. 2004; 198:535-566) and time integration is performed with the help of a four-stage Runge-Kutta method. Numerical properties of the proposed scheme are investigated both, analytically using linear spectral analysis, and numerically for highly nonlinear cases. The numerical analysis indicates that the newly developed scheme has wider stability regions and better spectral resolution than most of the previously published numerical methods used to handle equivalent set of equations. Moreover, it was also noticed that the use of mixed-order strategies to discretize convective and dispersive terms may result in an important overall reduction of the spectral resolution of the scheme. Additionally, there is some numerical evidence, which seems to indicate that the incorporation of a high-order dispersion correction term as given by Madsen et al. (Coastal Eng. 1991; 15:371-388) may introduce instability in the system. Copyright (c) 2006 John Wiley & Sons, Ltd.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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
  • Thumbnail Image
    Item
    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).
  • No Thumbnail Available
    Item
    Integrating tsunami simulations in web applications using BROWNI, an open source client-side GPU-powered tsunami simulation library
    (2022) Galaz, J.; Cienfuegos, R.; Echeverria, A.; Pereira, S.; Bertin, C.; Prato, G.; Karich, J. C.
    Tsunami simulation software is a key component of state-of-the-art early warning systems but the inherent complexities in phases of installation, execution, pre and post-processing prevent their use in other areas of risk management such as communication and education. Recent advances in software and computational capacities such as the efficiency of GPU computing and the ubiquity of web browsers bring new opportunities to bridge the gap between expert and non-expert users. Here we present a Javascript library to enable a web browser to facilitate gathering and analyzing data from tsunami simulations, by means of interactive and efficient visualizations. At its core, the library uses WebGL, the browser's standard 3D graphics API, to run GPU accelerated computations of a tsunami model. A far-field tsunami model is implemented (linear shallow water equations discretized on spherical coordinates), and its implementation is validated against real tsunami observations, and benchmarked with two other tsunami software-packages. Two software platforms that use this library are presented to illustrate the powerful applications that can be developed for risk communication and education. These applications are characterized by their interactivity and fast computations, which enable users to focus on the understanding of the phenomena of tsunami propagation and iterate quickly to assess different scenarios and potential implications to tsunami risk management. Some limitations on this approach are discussed, in aspects such as scalability, performance, multi-threading and batch-processing, that can be relevant for other users. In our experience, the before mentioned benefits very well compensate the discussed limitations for this kind of applications. The library has an open source license, and is meant to be imported without modifying its source code to facilitate the creation of new applications as the ones herein presented.
  • Thumbnail Image
    Item
    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.
  • No Thumbnail Available
    Item
    Performance of an RC building under seismic and tsunami actions in sequence via nonlinear dynamic analysis including soil-structure interaction
    (2022) Cortez, C.; Junemann, R.; Fernandez, C.; Urrutia, A.; Crempien, J. G. F.; Cienfuegos, R.
    This research presents a methodology to study the behavior of buildings subjected to seismic and tsunami loading in sequence, considering soil structure interaction effects through a complete dynamic analysis. The case-study building is an RC frame, which is assumed to be located in a coastal city in Chile, and built on sandy soil. A 3D Soil-Structure Interaction (SSI) model, including the non-linear behavior of both the structure and the soil using finite element method (FEM) was presented. Synthetic seismic ground motion records and tsunami inundation time histories were generated, consistent with the same earthquake source. Building performance was first assessed considering the SSI model for each hazard separately and compared to a Fixed Base (FB) model. Then, the SSI model was subjected to seismic and tsunami loading in sequence. Engineering Demand Parameters (EDPs) of roof displacement, interstory drift ratio (IDR) and reinforcement strain in beams and columns were analyzed. These EDPs presented a larger response to the tsunami when the response to the previous earthquake was larger. Finally, two vertical evacuation building scenarios were studied: the location of the refugees and the effect of an aftershock occurring simultaneously with the tsunami inundation. Results showed that the location of the ref-ugees did not generate significant differences in the building response, and the aftershock increased the response only when it coincided with the maximum tsunami force.
  • Thumbnail Image
    Item
    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.
  • No Thumbnail Available
    Item
    River mouths and coastal lagoons in central Chile
    (2017) Cienfuegos, R.; Campino, J.R.; Gironas Leon, Jorge Alfredo; Almar, R.; Villagrán, M.