Fluid Mechanics and Acoustics Laboratory - UMR 5509

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Daniel Bourgault - ISMER, Rimouski, Québec

Sediment resuspension and transport by breaking internal waves on ocean sloping boundaries

Vendredi 16 mars 2018, 11h, salle 105, Bat W1, ECL

 Sediment resuspension and transport by breaking internal waves on ocean sloping boundaries

Motivated by intriguing acoustic observations collected in the St. Lawrence Estuary, the resuspension, dispersal and transport of mud-like sediment by shoaling and breaking internal solitary waves (ISW) of depression on uniform slopes are studied with the help of idealized two-dimensional, nonhydrostatic numerical simulations. It is shown that during the shoaling process the resuspended sediment can be transported both shoreward and seaward. The shoreward upslope transport is done by boluses, i.e. by a series of internal waves of elevation that are produced during the shoaling process of the incoming waves. These boluses additionally contribute to sediment resuspension as they progress upslope. The seaward transport of sediment is accomplished within intermediate nepheloid layers, that is layers of mixed fluid of intermediate density that have been charged with sediment during the shoaling and breaking processes of the main incoming waves. A number of empirical relationships are found between the control parameters and properties of the suspended sediment such as the horizontal extent of the nepheloid layers, the total mass of resuspended sediment and the location on the slope of maximum bed erosion. The numerical results show remarkable qualitative similarities with the acoustic field observations and provide a plausible mechanism to interpret the acoustic patterns observed in the field.

Daniel Bourgault est professeur invité à l’École Centrale sur l’année 2017-2018. Il est présent au LMFA du 1 au 31 mars 2018.



  • Friday 16 March 2018 11:00-12:00 -

    Séminaire : Daniel Bourgault

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