Research. |
Minimum dissipation theorem for microswimmers
The ability of microswimmers to optimize their propulsion strategies is of paramount importance for their locomotion and survival at low Reynolds numbers. Although for perfectly spherical swimmers the dissipation in neutral-type swimming is minimal, even smaller deviations from a perfect spherical shape can result in new propulsion strategies, namely, those of puller- or pusher-type microswimmers. By minimizing dissipation for microswimmers, we determine the flow field of an optimal near-spherical swimmer and show that the optimal swimmer can be puller, pusher, or neutral, depending on the shape. Using an asymptotic approach, we found that among all the modes of the shape function, only the third mode determines the optimal swimming type.
Key publication:
A. Daddi-Moussa-Ider, B. Nasouri, A. Vilfan, and R. Golestanian, Optimal swimmers can be pullers, pushers or neutral depending on the shape, J Fluid Mech Rapids 922, R5 (2021).
The ability of microswimmers to optimize their propulsion strategies is of paramount importance for their locomotion and survival at low Reynolds numbers. Although for perfectly spherical swimmers the dissipation in neutral-type swimming is minimal, even smaller deviations from a perfect spherical shape can result in new propulsion strategies, namely, those of puller- or pusher-type microswimmers. By minimizing dissipation for microswimmers, we determine the flow field of an optimal near-spherical swimmer and show that the optimal swimmer can be puller, pusher, or neutral, depending on the shape. Using an asymptotic approach, we found that among all the modes of the shape function, only the third mode determines the optimal swimming type.
Key publication:
A. Daddi-Moussa-Ider, B. Nasouri, A. Vilfan, and R. Golestanian, Optimal swimmers can be pullers, pushers or neutral depending on the shape, J Fluid Mech Rapids 922, R5 (2021).
Optimal navigation strategies for active microswimmers
In contrast to the well-studied problem of how to steer a macroscopic object like an airplane or a lunar lander in order to optimally reach a destination, the quest for the optimal navigation strategy for microswimmers remains unsolved. Here we study this problem systematically and show that the characteristic flow field of microswimmers crucially influences the navigation strategy required to reach a destination faster. The resulting optimal trajectories can have remarkable and unintuitive shapes, qualitatively different from those of dry active particles or mobile macroagents. Our results provide generic insights into the role of hydrodynamics and fluctuations in optimal microscale navigation and suggest that microorganisms may have survival advantages by strategically controlling their distance to distant walls.
Key publication:
A. Daddi-Moussa-Ider, H. Löwen, and B. Liebchen, Hydrodynamics can determine the optimal route for microswimmer navigation, Commun. Phys. 4, 15 (2021).
In contrast to the well-studied problem of how to steer a macroscopic object like an airplane or a lunar lander in order to optimally reach a destination, the quest for the optimal navigation strategy for microswimmers remains unsolved. Here we study this problem systematically and show that the characteristic flow field of microswimmers crucially influences the navigation strategy required to reach a destination faster. The resulting optimal trajectories can have remarkable and unintuitive shapes, qualitatively different from those of dry active particles or mobile macroagents. Our results provide generic insights into the role of hydrodynamics and fluctuations in optimal microscale navigation and suggest that microorganisms may have survival advantages by strategically controlling their distance to distant walls.
Key publication:
A. Daddi-Moussa-Ider, H. Löwen, and B. Liebchen, Hydrodynamics can determine the optimal route for microswimmer navigation, Commun. Phys. 4, 15 (2021).