Shiyuan Hu
Beihang University
Effects of Hydrodynamic Interactions in Microalgal Swimming
Many eukaryotic microorganisms swim at low Reynolds number by beating multiple flagella. We model the dynamics of multiflagellate swimmers resembling microalgae. When flagella are actuated synchronously, the swimming efficiency can be enhanced or reduced by interflagellar hydrodynamic interactions (HIs), which are determined by the intrinsic tilting angle of the flagella. The asynchronous gait with a phase difference between neighboring flagella can reduce oscillatory motion via the basal mechanical coupling. In addition, in the presence of a cell body, simulations that take into account the body-flagella interactions reveal the advantage of the anterior configuration of flagella compared with the posterior configuration, where in the latter case an optimal flagella number arises. We demonstrate that body-flagella HIs significantly enhance swimming speed and efficiency. This is contrary to the common intuition that the cell body acts as a passive load for swimming. As the body size increases, the competition between the enhanced body-flagella HIs and the increased viscous drag leads to an optimal body size for swimming. Our results have implications for both microalgal swimming and laboratory designs of biohybrid microrobots.
References:
1. S. Hu and F. Meng, Multiflagellate Swimming Controlled by Hydrodynamic Interactions, Phys. Rev. Lett. 132, 204002 (2024).
2. X. Hu, Z. Liu, D. Wei, and S. Hu, Passive cell body plays active roles in microalgal swimming via nonreciprocal interactions, arXiv:2507.19152 [physics.flu-dyn].
Profile: Shiyuan Hu obtained his Ph.D. in physics from New York University in 2022. He then worked as a postdoctoral researcher at the Institute of Theoretical Physics, Chinese Academy of Sciences, from 2022 to 2024. He is currently an assistant professor in the Department of Physics at Beihang University in Beijing. His research focuses on fluid dynamics and soft matter physics. He employs numerical and theoretical methods, such as PDEs, boundary integral method, and asymptotic analysis, to study problems including biological locomotion and transport dynamics in fluid flows.
