Macroscopic pilot-wave dynamics in density-stratified fluids
| When |
May 12, 2025
from 11:00 to 12:00 |
|---|---|
| Where | Salle des thèses |
| Contact Name | Louis Couston |
| Attendees |
Patrice Le Gal |
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Our recent experiments with particles called ludions (or Descartes divers) immersed in a salt-stratified water layer reveal the resonance between the ludion forced oscillations and the internal gravity wave field. These experiments show also the spontaneous self-propulsion of the particle in the horizontal plane. To uncover the wave-particle interactions underlying this propulsion, direct two-dimensional lattice Boltzmann / immersed-boundary simulations were conducted. A minimal hydrodynamic theory shows that the propulsion is due to the Doppler effect that modifies the angles of the internal gravity wave vectors and breaks the forward/backward symmetry of the system. In bounded domains, internal waves reflected from the walls react back on the ludion and create a radiative force that derives from a Casimir-like potential. Despite the presence of the Doppler force, this potential governs the ludion long-term dynamics, leading to capture the ludion in fixed points for the simplest cases or chaotic attractors near the potential wells. Our fi ndings establish the ludion as a novel hydrodynamic pilot-wave system, that may offer a new platform for exploring macroscopic wave-particle duality.
- P. Le Gal, B. Morales Castillo, S. Hernandez-Zapata and G. Ruiz Chavarria, G. J. Fluid Mech., 931, A14, (2022).
- S. Gsell and P. Le Gal, https://doi.org/10.48550/arXiv.2501.04402, (2025).