University of Toulon | PhD in dynamics and self-organization of self-propelled agents

Summary

Many natural systems, such as schools of fish, flocks of birds, or bacterial colonies, exhibit emergent behaviors resulting from both interactions between agents and hydrodynamic interactions with the environment [1-3]. Understanding these phenomena at the intersection of dynamical systems, fluid mechanics, self-organization, and multi-agent modeling is crucial for numerous applications.

Harnessing ambient fluid flows has the potential to significantly improve an agent’s range and speed, enabling, for example, more economical movement [4]. When several agents move simultaneously in the same environment, exploiting the properties of the generated flows opens the way to remarkable natural configurations and collective modes of navigation, potentially even more efficient in terms of range, speed, or energy consumption. In this context, we will focus on self-propelled agents operating at high Reynolds numbers and on non-autonomous flows that can lead to chaotic advection [5]. To explore these mechanisms, the dynamic properties will be analyzed using Lagrangian coherent structures, which provide a relevant framework for characterizing organization and transport within the fluid [6], employing Lagrangian tools [7] and other complexity functions [8].

The work will aim for applications in the design of robotic systems such as underwater drone swarms, based on navigation dynamics grounded in these hydrodynamic properties. The thesis will combine theoretical approaches and numerical simulations. Proficiency in computer tools (programming languages ​​such as Fortran95, C, C++) and data analysis tools (Octave, Matlab, Python) is required.

References:

1. Ko, H., Lauder, G. and Nagpal, R., 2023. The role of hydrodynamics in collective motions of fish schools and bioinspired underwater robots. Journal of the Royal Society Interface, 20(207).
2. Timm, ML, Pandhare, RS and Masoud, H., 2024. Multi-body hydrodynamic interactions in fish-like swimming. Applied Mechanics Reviews, 76(3), p.030801.
3. Filella, A., Nadal, F., Sire, C., Kanso, E. and Eloy, C., 2018. Model of collective fish behavior with hydrodynamic interactions. Physical review letters, 120(19), p.198101.
4. Gunnarson, P. and Dabiri, JO, 2025. Surfing vortex rings for energy-efficient propulsion. PNAS nexus, 4(2), p.pgaf031.
5. Leoncini, X., Agullo, O., Muraglia, M. and Chandre, C., 2006. From chaos of lines to Lagrangian structures in flux conservative fields. The European Physical Journal B-Condensed Matter and Complex Systems, 53(3), pp.351-360.
6. Haller, G., 2015. Lagrangian coherent structures. Annual review of fluid mechanics, 47(1), pp.137-162.
7. Daquin, J., Pédenon-Orlanducci, R., Agaoglou, M., Garcia-Sanchez, G. and Mancho, A.M., 2022. Global dynamics visualisation from Lagrangian Descriptors. Applications to discrete and continuous systems. Physica D: Nonlinear Phenomena, 442, p.133520.
8. Faranda, D., Leoncini, X. and Vaienti, S., 2014. Mixing properties in the advection of passive tracers via recurrences and extreme value theory. Physical Review E, 89(5), p.052901.

Objective and Context

This thesis aims to study the dynamic and hydrodynamic properties of self-propelled agents. The objectives include understanding fundamental mechanisms related to self-organization, developing powerful numerical tools, and analyzing data from simulations. It is expected that the work will result in several publications in international peer-reviewed journals (such as Physical Review Letters, Physical Review E, and Nonlinearity) and presentations at national and international conferences. The implications of this thesis concern both fundamental research and potential applications for robotic systems of underwater drone swarms where navigation strategies include and rely on hydrodynamic properties.

This doctoral thesis aligns with a strategic focus of the University of Toulon (UTLN) centered on marine physics and the dynamics of underwater drones. The doctoral candidate will join the laboratory of the Center for Theoretical Physics (CPT) and will be a member of the “nonlinear dynamics” team, which benefits from several national and international collaborations (Denmark, Mexico, China, magnetic confinement fusion federation, to name just a few) in synergy with the thesis themes.

Desired profile

The thesis combines theoretical and numerical approaches. Theoretically, knowledge of dynamical systems theory, Hamiltonian chaos, fluid mechanics, and statistical physics is desirable. Numerically, knowledge of programming languages ​​(such as Fortran 95, C, C++) is required, as well as data analysis tools (such as Octave, Matlab, or Python). TO APPLY, PLEASE SEND THE FOLLOWING DOCUMENTS TO jerome.daquin@cpt.univ-mrs.fr:

• Master’s degree transcripts (M1 & M2) or equivalent diploma,
• cover letter,
• detailed CV,
• letter(s) of recommendation.

Objective of promoting the work

This thesis aims to study the dynamic and hydrodynamic properties of self-propelled agents. The objectives include understanding fundamental mechanisms related to self-organization, developing powerful numerical tools, and analyzing data from simulations. It is expected that the work will result in several publications in international peer-reviewed journals (such as Physical Review Letters, Physical Review E, and Nonlinearity) and presentations at national and international conferences. The implications of this thesis concern both fundamental research and potential applications for robotic systems of underwater drone swarms where navigation strategies include and rely on hydrodynamic properties.

Application and more details: https://app.doctorat.gouv.fr/proposition?id=13184