Nicolas Mordant

Host Institution: UJF

Laboratory: LEGI

Call for projects: Consolidator (PE3)

Project Name: WATU – Wave turbulence: beyond weak turbulence

Amount: €1,991,611

Description :

Wave turbulence and fluid turbulence belong to the same class of turbulent states consisting of a large number of nonlinearly coupled degrees of freedom driven away from equilibrium.

Weak turbulence theory is a statistical theory of low amplitude turbulent waves.

The predicted phenomenology (energy cascade) is very similar to that of fluid turbulence, which sorely lacks such a statistical theory.

Weak turbulence is therefore a promising mathematical framework for turbulence in general.

It is observed in many systems such as planetary atmospheres, astrophysical plasmas, tokomak fusion plasmas, superfluid turbulence or Bose-Einstein condensates for example.

The theory is much less advanced in the case of strong wave turbulence for which a richer phenomenology appears due to the generation of coherent structures.

Moreover, to a large extent, the theory lacks experimental validation.

My project aims to study several physical systems (vibrating elastic plate, 1D and 2D water surface waves, 3D internal waves in a stratified fluid) specifically chosen to highlight various characteristics of wave turbulence both in the regimes weak and strong.

Under strong forcing, coherent structures will appear such as developable cones (elastic plates), solitons and sharp water wave crests (water surface waves) or fluid turbulence to overturn 3D internal waves.

In particular, I will use two unique large-scale facilities available at LEGI (Grenoble, France): the 30m 1D wave flume for surface waves and the 13m diameter Coriolis turntable for surface waves and internal waves.

I will implement advanced space-time resolved profilometry and velocimetry techniques tailored to the dimensionality and size of each of these systems.

Advanced statistical tools on massive datasets will provide deep insight into the coupling between waves and structures in different wave turbulence regimes.