2015/11/04 by Massimo Cencini, M. Franchino, Cencini, M. +5
Environmental Science · Medicine · Physics and Astronomy · #Aquatic Ecosystems and Phytoplankton Dynamics #Biological Physics (physics.bio-ph) #FOS: Biological sciences #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Micro and Nano Robotics #Quantitative Methods (q-bio.QM) #Spaceflight effects on biology
paper · pdf · doi:10.48550/arxiv.1511.01255
openalex publication_date 2015/11/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A suspension of gyrotactic microalgae Chlamydomonas augustae swimming in a cylindrical water vessel in solid-body rotation is studied. Our experiments show that swimming algae form an aggregate around the axis of rotation, whose intensity increases with the rotation speed. We explain this phenomenon by the centripetal orientation of the swimming direction towards the axis of rotation. This centripetal focusing is contrasted by diffusive fluxes due to stochastic reorientation of the cells. The competition of the two effects lead to a stationary distribution, which we analytically derive from a refined mathematical model of gyrotactic swimmers. The temporal evolution of the cell distribution, obtained via numerical simulations of the stochastic model, is in quantitative agreement with the experimental measurements in the range of parameters explored.