MechE Colloquium: Problems of Planktonic Navigation

Event details

Date 17.03.2026
Hour 12:00 ’ 13:00
Speaker Prof. Christophe Eloy , Centrale Méditerranée ,  IRPHE institute ,  Aix-Marseille Université
Location

Abstract: Plankton face the challenging task of navigating oceanic turbulence using only hydrodynamic and chemical cues to escape predators or catch prey. This seminar focuses on one of such tasks: the problem of vertical navigation in turbulence or how a microscopic swimmer can move upward or downward using only local velocity gradients.
I first present a theoretical model showing that an optimal swimming direction can be derived under locally steady flow conditions. Numerical simulations reveal that organisms following this strategy can surf on turbulence, achieving vertical speeds of twice their own swimming speed. Experiments with larval snails support this mechanism. I then discuss how reinforcement learning recovers similar strategies in complex flows and conclude by showing how passive flexible bodies can reproduce these behaviours through fluid-structure interactions alone.

Biography: Christophe is a Professor of Mechanical Engineering at Centrale Méditerranée, working at the "Institut de recherche sur les phénomènes hors équilibre" (IRPHE, Marseille). Physicist by training, his work combines mathematical models, numerical simulations, and experiments at the interface of physics, mechanics, applied mathematics, and biology. His current research themes include fluid-structure interactions, locomotion across scales, the growth and form of trees, collective motion, bio-inspired robotics, and plankton behavior.

• Contact
• EPFL CH-1015 Lausanne
• 0041 (0)21 693 11 11