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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 5: Active Matter I (joint session BP/CPP/DY)

CPP 5.8: Talk

Monday, March 18, 2024, 11:30–11:45, H 1028

Energetic cost of microswimmer navigation: the role of body shape — •Lorenzo Piro^1,2, Andrej Vilfan^1,3, Ramin Golestanian^1,4, and Benoît Mahault¹ — ¹Max Planck Institute for Dynamics and Self-Organization (MPI-DS), 37077 Goettingen, Germany — ²Department of Physics and INFN, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy — ³Jozef Stefan Institute, 1000 Ljubljana, Slovenia — ⁴Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3PU, United Kingdom

We study the energetic efficiency of navigating microswimmers by explicitly taking into account the geometry of their body. We show that, whereas arguments based solely on propulsion efficiency lead to the conclusion that needle-like swimmers are most energetically efficient, disk-like swimmers rotated by flow gradients naturally follow time-optimal trajectories. The coupling between body geometry and hydrodynamics thus leads to a generic trade-off between the energetic costs associated with propulsion and navigation, which is accompanied by the selection of a finite optimal aspect ratio. We derive from optimal control theory the steering policy ensuring overall minimum energy dissipation and characterize how navigation performances vary with the swimmer shape. Our results highlight the important role of the swimmer geometry in realistic navigation scenarios.

Keywords: Optimal navigation; Microswimmers; Optimal control theory; Hydrodynamics; Living matter