Gravity waves at the water surface
At wavelengths much larger than 1 cm, the physics of water surface waves is governed by gravity. In the ocean waves are forced by the wind and their nonlinear interaction yields to a turbulent state as shown in the picture below.
Picture of the Mediterranean Sea near Ajaccio, Corsica
In the ocean, the conditions are often not stationary and the parameters are hard to characterize. Thus we perform experiments in the lab to benefit from well controlled conditions. We study such gravity wave turbulence in the Coriolis facility which is 13m in diameter, 1m deep (see picture on the right). Waves are forced with two wedge wavemakers as shown in the video below.
After a 10min transient we obtain a turbulent states that resembles somehow the one from the sea shown above (see video below)
The goal is then to measure the wave elevation. We use a stereoscopic technique based on image correlations. The first issue is to be able to see the water surface. We use tiny slightly buoyant polystyrene particles to make the water surface visible.
By using image correlations, we can then reconstruct the 3D shape of the water surface.
We can then perform statistical analyses of the wave field. With Quentin Aubourg and Antoine Campagne, we observed in particular the role of bound waves on the nonlinear dynamics of the wave field (see bibliography section to get the articles). We also compared our results with field data provided by Fabrice Ardhuin.
