Reference : UMR8523-STERAN-001
Workplace : VILLENEUVE D ASCQ
Date of publication : Tuesday, May 3, 2022
Scientific Responsible name : Stéphane Randoux
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 3 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Since the work of Joseph Fourier, it is known that any wave can be represented as a superposition of plane waves, characterized by a unique wavelength and frequency. Extraordinarily powerful when these plane waves are independent, this representation breaks down in strongly nonlinear systems, especially in turbulent regime, where this approach is blurred by the strong interactions between components of different frequencies.
However, there are remarkable nonlinear waves, called solitons, which are very localized and can propagate over large distances without deforming, or crossing each other without noticeable changes. A fundamental question is then to know if any nonlinear turbulent wave can be represented as a "soliton gas", where a large number of solitons are "superposed". Nonlinear spectral analysis methods, based on the Inverse Scattering Transform theory, allow to identify the soliton content of an arbitrary wave, which remains unchanged during the propagation because of the soliton properties. As in statistical physics, the macroscopic behavior of a soliton gas can be described by a kinetic theory which is interested in defining analogues of pressure or temperature and in relating them to microscopic interactions between solitons.
The objective of the thesis is to carry out new experiments in optics and hydrodynamics aiming at confronting some results of the kinetic theory of soliton gases to the experiment and more generally, to examine the wave turbulence, through the prism of the physics of integrable systems.
Realization of optical fiber experiments at PhLAM lab. Participation to water wave experiments at LEGI Lab (Grenoble), MSC Lab (Paris) and LHEEA Lab (Nantes).
We talk about it on Twitter!