Browsing by Author "Michallet, H."

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    Barred-beach morphological control on infragravity motion
    (2012) Almar, R.; Cienfuegos Carrasco, Rodrigo Alberto; Gonzalez, Eduardo; Catalán, P.; Michallet, H.; Bonneton, P.; Castelle, B.; Suarez, L.
    A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.
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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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    Nearshore bathymetric inversion from video using a fully non-linear Boussinesq wave model
    (2011) Cienfuegos Carrasco, Rodrigo Alberto; Almar, R.; Birrien, F.; Castelle, B.; Catalán, P.; Michallet, H.
    This paper presents a new depth inversion methodology from video imagery. The strength of the method is the use of a fully non-linear Boussinesq wave model in combination with a very complete video-derived laboratory wave observation that includes period, celerity and wave height. Compared to the previous use of wave dispersion formulas, here the better description of wave dynamics substantially improves bathymetry estimation. For the considered laboratory case, error on bathymetry is as small as 8 % whereas other formulations, shallow water or non-linear derived solution can only attain 24 % and 14 %, respectively. More in-depth analysis on the error shows a fair sensitivity on video-derived breaker height and describes the large contribution of non-linearities. The recent possibility of using Serre's dispersion relation in combination with video-derived wave height provides a reasonable performance and should be further envisaged for one-dimensional depth inversion. Future extensions of this work involve the use of a two-dimensional Boussinesq model to include more hydrodynamics processes such as wave-driven circulation over three-dimensional surfzone sandbars.
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    Vertical distribution of Skewness and asymmetry in a boundary layer on a mobile bed. Experiment and k-omega model comparison
    (2014) Suárez Atias, Leandro; Barthelemy, E.; Berni, C.; Chauchat, J.; Michallet, H.; Cienfuegos Carrasco, Rodrigo Alberto