Description du sujet de thèse

The objective of this thesis is to experimentally and numerically investigate the interaction between surface waves on a liquid and complex, deformable floaters. This fluid–structure interaction problem arises in various contexts, notably in the transport and dispersion of marine pollutants such as microplastics.

The first part of the study will focus on the motion of individual floaters, emphasizing capillary effects. The aim is to understand how the interaction between the menisci surrounding the floater and the wave field can generate second-order motions that lead to preferential orientations of the floaters.

In the second part, the focus will shift to the collective dynamics of floaters and their feedback on the flow. The presence of a large number of floaters at the surface can give rise to nontrivial collective behavior: floaters may self-organize into cohesive "rafts" and effectively behave as a viscoelastic solid, thereby modifying the wave dynamics.

Characterizing this complex rheology will provide improved models for pollutant dispersion in natural environments. The doctoral candidate will design and conduct original experiments to study these phenomena using facilities available at the FAST laboratory (wave tanks, velocimetry, optical surface reconstruction), and will also develop theoretical models and numerical simulations to be compared with experimental data.

Contexte de travail

The PhD will be conducted within the group "Instabilities, Waves, and Turbulence" at the laboratory FAST , under the supervision of Frédéric Moisy and Wietze Herreman. It will involve collaboration with two research teams from the PMMH laboratory (ESPCI) and the Institut d'Alembert (Sorbonne University), as part of the ANR project Transwaves.

Contraintes et risques

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