Matthieu Ménard
Professional homepage
Short research statement
I am mainly interested in mean-field kinetic theory. Namely, I try to describe the statistical behavior of numerous particles interacting through a long-range potential. The average behavior of such a system is described by a Vlasov-like partial differential equation. Justifying this behavior boils down to proving a law of large numbers (or a "mean-field limit") for the particle system.

In my PhD thesis [T], I worked with the "modulated energy" method introduced by Duerinckx and Serfaty, which is particularly convenient to prove mean-field limits of systems of particles with singular interactions coming from many physical backgrounds. I adapted this method to two different systems related to fluid dynamics: In my current position, I am interested in the long-time behavior and fluctuations of particle systems. With Armand Bernou and Mitia Duerinckx, we studied in [4] the creation of chaos phenomenon for interacting Brownian particles: starting initially from an arbitrary exchangeable N-particle distribution, whe show that the mean-field approximation holds with an accuracy O(N-1), up to an error due solely to initial pair correlations, which is damped exponentially over time. This is complemented by corresponding results on higher-order creation of chaos in the form of higher-order correlation estimates.

Besides kinetic theory, I worked on spectral theory with Christophe Lacave and Catherine Sulem. We studied in [3] the spectrum of the Dirichlet-Neumann operator that characterizes the propagation of linear water waves. We showed that when the bottom is small and periodic, some conditions on its Fourier coefficients ensure the apparition of small gaps in the spectrum of the Dirichlet-Neumann operator.

Preprints
[4]     Creation of chaos for interacting Brownian particles
with Armand Bernou and Mitia Duerincx.
Submitted (2025)

Publications
[3]     Bloch-Floquet band gaps for water waves over a periodic bottom
with Christophe Lacave and Catherine Sulem,
EMS Surveys in Mathematical Sciences (2025)
[2]     Mean-Field Limit of Point Vortices for the Lake Equations
Communications in Mathematical Sciences (2024)
[1]     Mean-Field Limit Derivation of a Monokinetic Spray Model with Gyroscopic Effects
SIAM Journal on Mathematical Analysis (2024)
The preprints of these publications can be found on arXiv and on Hal.

PhD thesis
[T]      Mean-field limits in fluid mechanics and kinetic theory
PhD thesis, co-supervised by Christophe Lacave and Evelyne Miot (defended on December 13th, 2023).