%0 Journal Article
%T Effect of a submerged plate on the near-bed dynamics underincoming waves in deep water conditions
%+ Institut méditerranéen d'océanologie (MIO)
%A Rey, Vincent
%A Touboul, Julien
%A Sous, Damien
%< avec comité de lecture
%Z MIO:15-038
%@ 0141-1187
%J Applied Ocean Research
%I Elsevier
%P 67-74
%8 2015-08-31
%D 2015
%R 10.1016/j.apor.2015.07.003
%Z Sciences of the Universe [physics]/Ocean, Atmosphere
%Z Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]Journal articles
%X It is well known that wave induced bottom oscillations become more and morenegligible when the water depth exceeds half the wavelength of the surfacegravity wave. However, it was experimentally demonstrated for regular wavesthat the bottom pressure oscillations at both first and second wave harmonicfrequencies could be significant even for incoming waves propagating in deepwater condition in the presence of a submerged plate. For a water depth h of about the wavelength of the wave, measurementsunder the plate (depth immersion of top of plate h/6, length h/2) have shownbottom pressure variations at the wave frequency, up to thirty times largerthan the pressure expected in the absence of the plate. In this paper, notonly regular but also irregular wave are studied together with wavefollowing current conditions. This behavior is numerically verified by useof a classical linear theory of waves. The wave bottom effect is explainedthrough the role of evanescent modes and horizontally oscillating watercolumn under the plate which still exist whatever the water depth. Such amodel, which allows the calculation of the velocity fields, has shown thatnot only the bottom pressure but also the near bed fluid velocity isenhanced. Two maxima are observed on both sides of the location of theplate, at a distance of the plate increasing with the water depth. Thepossible impact of such near bed dynamics is then discussed for fieldconditions thanks to a scaling based on a Froude similarity. It isdemonstrated that these structures may have a significant impact at the seabed even in very deep water conditions, possibly enhanced in the presence ofcurrent.
%G English
%L hal-01188574
%U https://hal.science/hal-01188574
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%~ CNRS
%~ UNIV-AMU
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