arXiv subjects

Henri Didelle

Publications and source records attributed to Henri Didelle.

4 recordsLinked to original sources

arXiv2015

A laboratory study of low-mode internal tide scattering by finite-amplitude topography

We present the first laboratory experimental results concerning the scattering of a low-mode internal tide by a gaussian topography. Experiments performed at the Coriolis Platform in Grenoble used a recently-conceived internal wave generator as a means of producing a high-quality mode-1 wave field. The evolution of the wave field in the absence and presence of a supercritical Gaussian was studied by performing spatiotemporal modal decompositions of velocity field data obtained using Particle Image Velocimetry (PIV). The results support predictions that large-amplitude supercritical topography produces significant reflection of the internal tide and transfer of energy from low to high modes.

physics.ao-ph↗

arXiv2015

Large-scale, realistic laboratory modeling of M2 internal tide generation at the Luzon Strait

The complex double-ridge system in the Luzon Strait in the South China Sea (SCS) is one of the strongest sources of internal tides in the oceans, associated with which are some of the largest amplitude internal solitary waves on record. An issue of debate, however, has been the specific nature of their generation mechanism. To provide insight, we present the results of a large-scale laboratory experiment performed at the Coriolis platform. The experiment was carefully designed so that the relevant dimensionless parameters, which include the excursion parameter, criticality, Rossby, and Froude numbers, closely matched the ocean scenario. The results advocate that a broad and coherent weakly nonlinear, three-dimensional, M2 internal tide that is shaped by the overall geometry of the double-ridge system is radiated into the South China Sea and subsequently steepens, as opposed to being generated by a particular feature or localized region within the ridge system.

physics.ao-ph↗

arXiv2006

A novel internal waves generator

We present a new kind of generator of internal waves which has been designed for three purposes. First, the oscillating boundary conditions force the fluid particles to travel in the preferred direction of the wave ray, hence reducing the mixing due to forcing. Secondly, only one ray tube is produced so that all of the energy is in the beam of interest. Thirdly, temporal and spatial frequency studies emphasize the high quality for temporal and spatial monochromaticity of the emitted beam. The greatest strength of this technique is therefore the ability to produce a large monochromatic and unidirectional beam.

physics.ao-ph↗

arXiv2006

Quantitative laboratory observations of internal wave reflection on ascending slopes

Internal waves propagate obliquely through a stratified fluid with an angle that is fixed with respect to gravity. Upon reflection on a sloping bed, striking phenomena are expected to occur close to the slope. We present here laboratory observations at moderately large Reynolds number. A particle image velocimetry (PIV) technique is used to provide time resolved velocity fields in large volumes. The generation of the second and third harmonic frequencies are clearly demonstrated in the impact zone. The mechanism for nonlinear wavelength selection is also discussed. Evanescent waves with frequency larger than the Brunt-Väisälä frequency are detected and experimental results agree very well with theoretical predictions. The amplitude of the different harmonics after reflection are also obtained.

nlin.PS↗