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3 resultados encontrados para: AUTOR: Diez, Carlos E.
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A 2D image-based approach for CFD validation of liquid mixing in a free-surface condition
Rodríguez Ocampo, P. E. (autor) ; Ring, M. (autor) ; Hernández Fontes, J. V. (autor) ; Alcérreca Huerta, Juan Carlos (autor) ; Mendoza Ramírez, Eduardo (autor) ; Gallegos Diez Barroso, Gabriel (autor) ; Silva, R. (autor) ;
Disponible en línea
Contenido en: Journal of Applied Fluid Mechanics Volume 13, número 5 (2020), p. 1487-1500 ISSN: 1735-3645
Resumen en: Inglés |
Resumen en inglés

This study proposes an image-based approach to evaluate the validity of numerical results for cases where the setup can be assumed to be two-dimensional (2D) and mixing between liquids of different densities occurs under a free-surface condition. The proposed methodology is based on the estimation of the relative errors of the model through density matrices generated from images of the experimental and numerical results (i.e., post-processing snapshots of the density field). To demonstrate the use of the methodology, experimental tests and numerical simulations were performed for a double-dam-break problem with two miscible liquids. For the experiments, a high-speed camera was employed to capture details of the fluid interactions after the dam breaking. For the numerical simulations, an OpenFOAM® multiphase solver was employed to reproduce the benchmarking tests. Three turbulence approaches were tested: a zero-equation RANS model, a two-equation (k-epsilon) RANS model, and a Large-Eddy Simulation (LES) model. The experimental results compared favorably against the numerical results, with average drelative errors of ~17 and ~19% for the zero-equation and the two-equation turbulence models, respectively, and ~14% for the LES model. From the results obtained, it can be inferred that the two-equation (k-epsilon) model had limitations in reproducing the mixing between the liquid phases in terms of relative errors. The LES model reproduces the mixing between phases more accurately than zero and two-equation RANS models, which were seen to be more suitable for capturing the formation of large eddies in the initial phase of the experiment. The present methodology canbe improved and extended for different multiphase flow configurations.

Resumen en: Inglés |
Resumen en inglés

Marine renewables represent a promising and innovative alternative source for satisfying the energy demands of growing populations while reducing the consumption of fossil fuels. Most technological advancements and energy yield assessments have focused on promoting the use of kinetic energy from tidal streams with flow velocities higher than 2.0 m s−1 . However, slower-moving flows from ocean currents are recently explored due to their nearly continuous and unidirectional seasonal flows. In this study, the potential of the Yucatan Current was analysed at nearshore sites over the insular shelf of Cozumel Island in the Mexican Caribbean. Field measurements were undertaken using a vessel-mounted Acoustic Doppler Current Profiler (ADCP) to analyse the spatial distribution of flow velocities, along with Conductivity-temperature-depth (CTD) profiles as well as data gathering of bathymetry and water elevations. Northward directed flow velocities were identified, with increasing velocities just before the end of the strait of the Cozumel Channel, where average velocities in the region of 0.88–1.04 m s−1 were recorded. An estimation of power delivery using horizontal axis turbines was undertaken with Blade Element Momentum theory. It was estimated that nearly 3.2 MW could be supplied to Cozumel Island, amounting to about 10% of its electricity consumption.

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Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic
Bjorndal, Karen A. ; Bolten, Alan B. (coaut.) ; Chaloupka, Milani (coaut.) ; Saba, Vincent S. (coaut.) ; Bellini, Cláudio (coaut.) ; Marcovaldi, Maria A. G. (coaut.) ; Santos, Armando J. B. (coaut.) ; Wurdig Bortolon, Luis Felipe (coaut.) ; Meylan, Anne B. (coaut.) ; Meylan, Peter A. (coaut.) ; Gray, Jennifer (coaut.) ; Hardy, Robert (coaut.) ; Brost, Beth (coaut.) ; Bresette, Michael (coaut.) ; Gorham, Jonathan C. (coaut.) ; Connett, Stephen (coaut.) ; Van Sciver Crouchley, Barbara (coaut.) ; Dawson, Mike (coaut.) ; Hayes, Deborah (coaut.) ; Diez, Carlos E. (coaut.) ; van Dam, Robert P. (coaut.) ; Willis, Sue (coaut.) ; Nava, Mabel (coaut.) ; Hart, Kristen M. (coaut.) ; Cherkiss, Michael S. (coaut.) ; Crowder, Andrew G. (coaut.) ; Pollock, Clayton (coaut.) ; Hillis-Starr, Zandy (coaut.) ; Muñoz Tenería, Fernando A. (coaut.) ; Herrera Pavón, Roberto Luis (coaut.) ; Labrada Martagón, Vanessa (coaut.) ; Lorences, Armando (coaut.) ; Negrete Philippe, Ana (coaut.) ; Lamont, Margaret M. (coaut.) ; Foley, Allen M. (coaut.) ; Bailey, Rhonda (coaut.) ; Carthy, Raymond R. (coaut.) ; Scarpino, Russell (coaut.) ; McMichael, Erin (coaut.) ; Provancha, Jane A. (coaut.) ; Brooks, Annabelle (coaut.) ; Jardim, Adriana (coaut.) ; López Mendilaharsu, Maria de los Milagros (coaut.) ; González Paredes, Daniel (coaut.) ; Estrades, Andrés (coaut.) ; Fallabrino, Alejandro (coaut.) ; Martínez-Souza, Gustavo (coaut.) ; Vélez Rubio, Gabriela M. (coaut.) ; Boulon Jr., Ralf H. (coaut.) ; Collazo, Jaime A. (coaut.) ; Wershoven, Robert (coaut.) ; Guzmán Hernández, Vicente (coaut.) ; Stringell, Thomas B. (coaut.) ; Sanghera, Amdeep (coaut.) ; Richardson, Peter B. (coaut.) ; Broderick, Annette C. (coaut.) ; Phillips, Quinton (coaut.) ; Calosso, Marta (coaut.) ; Claydon, John A. B. (coaut.) ; Metz, Tasha L. (coaut.) ; Gordon, Amanda L. (coaut.) ; Landry Jr., Andre M. (coaut.) ; Shaver, Donna J. (coaut.) ; Blumenthal, Janice (coaut.) ; Collyer, Lucy (coaut.) ; Godley, Brendan J. (coaut.) ; McGowan, Andrew (coaut.) ; Witt, Matthew J. (coaut.) ; Campbell, Cathi L. (coaut.) ; Lagueux, Cynthia J. (coaut.) ; Bethel, Thomas L. (coaut.) ; Kenyon, Lory (coaut.) ;
Contenido en: Global Change Biology Vol. 23, no. 11 (November 2017), p. 4556–4568 ISSN: 1365-2486
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Resumen en: Inglés |
Resumen en inglés

Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles—hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta—exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)—the strongest on record—combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = −.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding.

We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study.