The Experts below are selected from a list of 311241 Experts worldwide ranked by ideXlab platform
Eric Barthélemy - One of the best experts on this subject based on the ideXlab platform.
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Wave boundary layer dynamics on a low sloping laboratory beach
2013Co-Authors: Dominic A. Van Der A, Eric Barthélemy, Dominique Mouazé, Laure Vignal, Paulo A. Silva, Tiago Abreu, Hervé MichalletAbstract:Wave-induced cross-shore sediment transport is driven by non-linear processes such as boundary layer streaming, Skewness and asymmetry, and the generation of infragravity waves. Most of our understanding of wave nonlinearity and associated wave boundary layer dynamics originates from studies involving relatively steep beach slopes (>1:40). Non-linearity on lower sloping beaches is expected to be of different character, which has prompted a series of laboratory experiments as part of the GLOBEX project on a 1:80 beach slope involving random, bichromatic and regular wave conditions. In this paper preliminary results are presented of high resolution wave boundary layer measurements in the surf zone obtained with a 2-component LDA system. The focus is on the time-averaged velocity near the bed, and the development of Skewness and asymmetry within the boundary layer. Results show that for all conditions there is a strong decrease in velocity asymmetry within the boundary layer which coincides with an increase in velocity Skewness, consistent with previous findings. When the vertical coordinate is appropriately scaled, a linear relationship appears between the velocity Skewness in the boundary layer and the velocity asymmetry and Skewness in the free-stream. Parameterizing this relationship for rough turbulent flow conditions could improve predictive capability of cross-shore sediment transport formulae.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: C. Berni, H. Michallet, Eric BarthélemyAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3 mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed which is found to be about 30 degrees and nearly constant over all the experiments made.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: Céline Berni, Eric Barthélemy, Hervé MichalletAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed, which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed that is found to be about 30ı and nearly constant over all the experiments made.
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Asymmetry and Skewness in the bottom boundary layer : Small scale experiments and numerical model
2012Co-Authors: Céline Berni, Léandro Suarez Atias, Hervé Michallet, Eric BarthélemyAbstract:This study investigates the non-linearities of wave boundary layer in the surf zone. It mainly focuses on the acceleration Skewness or asymmetry. Experiments [e.g. Grasso et al., 2011] show that asymmetry influences the sediment transport. Its influence resides in the fact that asymmetry in velocity (acceleration Skewness) tends to transform into velocity Skewness within the boundary layer. Analysis by Henderson et al. [2004] predicts a linear relation between Sk _b/Sk and As /Sk where Sk _b is the non dimensional Skewness near the bed, Sk the free-stream non-dimensional Skewness and As the free-stream non-dimensional asymmetry. Numerous experiments were carried out in the LEGI wave flume over a mobile bed composed of lightweight sediments. The quasi-random forcing is a repetition of 2 concatenated bichromatic wave packets. Vertical profiles of velocity are measured in the surf zone. A clear linear relation is shown between these two ratios. The experimental results are compared with the numerical results. A linear relation between Skewness and asymmetry is also obtained.
Hervé Michallet - One of the best experts on this subject based on the ideXlab platform.
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Wave boundary layer dynamics on a low sloping laboratory beach
2013Co-Authors: Dominic A. Van Der A, Eric Barthélemy, Dominique Mouazé, Laure Vignal, Paulo A. Silva, Tiago Abreu, Hervé MichalletAbstract:Wave-induced cross-shore sediment transport is driven by non-linear processes such as boundary layer streaming, Skewness and asymmetry, and the generation of infragravity waves. Most of our understanding of wave nonlinearity and associated wave boundary layer dynamics originates from studies involving relatively steep beach slopes (>1:40). Non-linearity on lower sloping beaches is expected to be of different character, which has prompted a series of laboratory experiments as part of the GLOBEX project on a 1:80 beach slope involving random, bichromatic and regular wave conditions. In this paper preliminary results are presented of high resolution wave boundary layer measurements in the surf zone obtained with a 2-component LDA system. The focus is on the time-averaged velocity near the bed, and the development of Skewness and asymmetry within the boundary layer. Results show that for all conditions there is a strong decrease in velocity asymmetry within the boundary layer which coincides with an increase in velocity Skewness, consistent with previous findings. When the vertical coordinate is appropriately scaled, a linear relationship appears between the velocity Skewness in the boundary layer and the velocity asymmetry and Skewness in the free-stream. Parameterizing this relationship for rough turbulent flow conditions could improve predictive capability of cross-shore sediment transport formulae.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: Céline Berni, Eric Barthélemy, Hervé MichalletAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed, which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed that is found to be about 30ı and nearly constant over all the experiments made.
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Asymmetry and Skewness in the bottom boundary layer : Small scale experiments and numerical model
2012Co-Authors: Céline Berni, Léandro Suarez Atias, Hervé Michallet, Eric BarthélemyAbstract:This study investigates the non-linearities of wave boundary layer in the surf zone. It mainly focuses on the acceleration Skewness or asymmetry. Experiments [e.g. Grasso et al., 2011] show that asymmetry influences the sediment transport. Its influence resides in the fact that asymmetry in velocity (acceleration Skewness) tends to transform into velocity Skewness within the boundary layer. Analysis by Henderson et al. [2004] predicts a linear relation between Sk _b/Sk and As /Sk where Sk _b is the non dimensional Skewness near the bed, Sk the free-stream non-dimensional Skewness and As the free-stream non-dimensional asymmetry. Numerous experiments were carried out in the LEGI wave flume over a mobile bed composed of lightweight sediments. The quasi-random forcing is a repetition of 2 concatenated bichromatic wave packets. Vertical profiles of velocity are measured in the surf zone. A clear linear relation is shown between these two ratios. The experimental results are compared with the numerical results. A linear relation between Skewness and asymmetry is also obtained.
Céline Berni - One of the best experts on this subject based on the ideXlab platform.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: Céline Berni, Eric Barthélemy, Hervé MichalletAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed, which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed that is found to be about 30ı and nearly constant over all the experiments made.
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Asymmetry and Skewness in the bottom boundary layer : Small scale experiments and numerical model
2012Co-Authors: Céline Berni, Léandro Suarez Atias, Hervé Michallet, Eric BarthélemyAbstract:This study investigates the non-linearities of wave boundary layer in the surf zone. It mainly focuses on the acceleration Skewness or asymmetry. Experiments [e.g. Grasso et al., 2011] show that asymmetry influences the sediment transport. Its influence resides in the fact that asymmetry in velocity (acceleration Skewness) tends to transform into velocity Skewness within the boundary layer. Analysis by Henderson et al. [2004] predicts a linear relation between Sk _b/Sk and As /Sk where Sk _b is the non dimensional Skewness near the bed, Sk the free-stream non-dimensional Skewness and As the free-stream non-dimensional asymmetry. Numerous experiments were carried out in the LEGI wave flume over a mobile bed composed of lightweight sediments. The quasi-random forcing is a repetition of 2 concatenated bichromatic wave packets. Vertical profiles of velocity are measured in the surf zone. A clear linear relation is shown between these two ratios. The experimental results are compared with the numerical results. A linear relation between Skewness and asymmetry is also obtained.
C. Berni - One of the best experts on this subject based on the ideXlab platform.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: C. Berni, H. Michallet, Eric BarthélemyAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3 mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed which is found to be about 30 degrees and nearly constant over all the experiments made.
H. Michallet - One of the best experts on this subject based on the ideXlab platform.
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Surf zone cross-shore boundary layer velocity asymmetry and Skewness: An experimental study on a mobile bed
Journal of Geophysical Research. Oceans, 2013Co-Authors: C. Berni, H. Michallet, Eric BarthélemyAbstract:An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3 mm from free-stream elevation down to the still bed level. The Skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity Skewness. A linear experimental relation between free-stream asymmetry to Skewness ratio and bottom Skewness to free-stream Skewness ratio is established. A theoretical linear relationship is discussed which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed which is found to be about 30 degrees and nearly constant over all the experiments made.
