Juliette Lancherez - Soft and active Brownian processes

Juliette Lacherez is a PhD candidate in the Théorie de la Matière Condensée group within Statistical Physics at Université de Bordeaux, working under the supervision of Thomas Salez and Yacine Amarouchène. Her research focuses on numerical approaches to complex physical systems, using simulations as a powerful tool to test theoretical models beyond experimental constraints. She primarily works with Langevin simulations to study nontrivial systems such as active swimmers in confined flows and colloids diffusing near deformable, fluctuating boundaries.

Time and place: –, Niels Henrik Abels hus, 7th floor, 723
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Motility of microscopic biological entities within crowed and complex environnements, with the aim of reaching specific targets, is a central question of biology, as evidenced by cancer metastasis, durotaxis of stem cells, self-assembly in tissues and organs, antibody recognition, DNA replication, or biofilm formation, among numerous other examples. In an idealization attempt, this problem could in principle be reduced to physics through a combination of a few essential ingredients: viscous flows, elastic boundaries, confinement, thermal fluctuations, and activity. The studies of passive and active motion in confined and soft-lubricated environments thus appear as canonical problems of biophysics. Despite the obvious character of this statement, studies are scarce on the topic, which is probably attributed to the difficulty of probing the associated effects experimentally.

My project naturally aims at filling this gap. By conducting numerical experiments, we investigate how activity and structured flows interplay and how canonical theories for passive colloids can be extended to active systems [1]. Furthermore, we develop and numerically check a new model for Brownian motion near soft and fluctuating boundaries [2], where intricate elastohydrodynamic couplings arise, following intriguing experimental results [3]. All of these developments aim at reaching fidelity to real biological environnements.

[1] M. Lagoin, J. Lacherez, G. de Tournemire, A. Badr, Y. Amarouchene, A. Allard, T. Salez, Enhanced dispersion of active microswimmers in confined flows, PNAS 122 (50) e2519691122, https://doi.org/10.1073/pnas.2519691122 (2025).

[2] J. Lacherez, M. Lavaud, Y. Amarouchene, D. S. Dean, T. Salez, Enhanced diffusion over a periodic trap by hydrodynamic coupling to an elastic mode. Comm. Phys 8, 465 , https://doi.org/10.1038/s42005-025-02378-6 (2025).

[3] N. Fares, M. Lavaud, Z. Zhang, A. Jha, Y. Amarouchene, T. Salez, Observation of Brownian elastohydrodynamic forces acting on confined soft colloids, PNAS 121 (42) e2411956121, https://doi.org/10.1073/pnas.2411956121 (2024).

Published Feb. 24, 2026 9:00 AM - Last modified Mar. 2, 2026 10:48 AM
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