Browsing by Author "Suarez, Leandro"

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    A snapshot of turbulence in the Northeastern Magellan Strait
    (2024) Lozovatsky, Iossif; Escauriaza, Cristian; Suarez, Leandro; Fernando, Harindra J. S.; Williams, Megan; Coppersmith, Ronald Scott; Mayorga, Nicolas
    First-ever measurements of the turbulent kinetic energy (TKE) dissipation rate in the northeastern Strait of Magellan (Seg-unda Angostura region) taken in March 2019 are reported here. At the time of microstructure measurements, the magnitude of the reversing tidal current ranged between 0.8 and 1.2 ms(-1). The probability distribution of the TKE dissipation rate in the water interior above the bottom boundary layer was lognormal with a high median value epsilon(MS)(med) = 1.2x10(-6) Wkg(-1). Strong vertical shear, (1-2)x10(-2) s(-1), in the weakly stratified water interior ensued a sub-critical gradient Richardson number Ri < 10(-1) - 10(-2). In the bottom boundary layer (BBL), the vertical shear and the TKE dissipation rate both decreased exponentially with the distance from the seafloor xi, leading to a turbulent regime with an eddy viscosity K-M similar to 10(-3) m(2)/s, which varied with time and location, while being independent of the vertical coordinate in the upper part of BBL (for xi > similar to 2 meters above the bottom).
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    Flow characterization and turbulence in the eastern section of the Strait of Magellan, Southern Chile
    (2024) Suarez, Leandro; Guerra, Maricarmen; Williams, Megan E.; Escauriaza, Cristian; Lozovatsky, Iossif; Coppersmith, Ronald; Fernando, Harindra Joseph S.
    The Strait of Magellan connects the Pacific and Atlantic oceans in South America's southern region, and it has been recognized for centuries as an important transoceanic navigation route as well as a unique marine environment with a rich ecological diversity. Evaluations of the impact of human activities in the channel and multiple potential future developments require abetter understanding of the physical environment to design sustainable strategies aimed at preserving these characteristics. In this investigation, we study the flow near the Atlantic inlet of the Strait where the dynamics is characterized by the interactions of the tide propagation within two narrows, which are the predominant features of the channel morphology. Tides amplified by the Patagonian shelf generate strong currents through these narrows and control the exchange between the Atlantic and central regions of the Strait. We employ bottom-mounted and vessel-mounted Acoustic Doppler Current Profilers (ADCPs) with tide gauges to analyze the mean flow, tidal propagation, and turbulence, complementing the data with previous available measurements. The analysis reveals residual flows directed toward ebb flow at the channel center and flood near the edges, showing a significant spring-neap variation. Turbulence statistics in the second narrows exhibit a significant variability between ebb and flood, with a balance between production and dissipation observed only during ebb phases.
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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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    Wave forced vorticity and dissipation scaling on a rip channeled beach
    (2023) Suarez, Leandro; Cienfuegos, Rodrigo; Michallet, Herve; Barthelemy, Eric
    Rip-currents, commonly observed on natural beaches, are vorticity induced and part of large scale near-shore circulations. The questions arise: how do bathymetric gradients magnitudes relate to rip velocities? how does rip current vorticity scale with wave characteristics and dissipation? What is the dynamics of the large scale 2D vorticity? To address these questions, we utilize a Non Linear Shallow Water model with a shock-capturing scheme. It is validated with preexisting experiments of wave induced rip-currents on uneven bathymetries generated by irregular waves. To do so the enstrophy (spatially averaged square of the vorticity) is shown to be a relevant metric to calibrate the bottom friction coefficient of the model. The numerical study based on a large number of simulations with monochromatic wave forcing shows that the more non-uniform the bathymetry is, the stronger the gradients in wave dissipation are and the stronger the enstrophy is. The rip current velocity is shown to linearly increase with the square root of the local enstrophy. The wave-averaged shallow water vorticity equation terms are evaluated. It is suggested that large scale 2D vorticity dynamics mainly result from an equilibrium between vorticity production, vorticity advection by the circulation and dissipation by bottom friction.& COPY; 2023 Elsevier Masson SAS. All rights reserved.