2014/10/07 by Francesco Santamaria, F. Santamaria, Filippo De Lillo +4 · 2 citations
Engineering · Physics and Astronomy · #Biology #Brownian motion #Classical mechanics #Ecology #Flow (mathematics) #Laminar flow #Mechanics #Micro and Nano Robotics #Orbital Angular Momentum in Optics #Particle Dynamics in Fluid Flows #Physics #Quantum mechanics #Reynolds number #Shear flow #Trapping #Turbulence #nlin.CD #physics.flu-dyn
paper · pdf · doi:10.1063/1.4900956
published as Phys. Fluids 26, 111901 (2014) · 12 pages, 12 figures
arxiv created 2014/10/07 · openalex publication_date 2014/11/01 · arxiv updated 2014/11/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Phytoplankton patchiness, namely the heterogeneous distribution of microalgae over multiple spatial scales, dramatically impacts marine ecology. A spectacular example of such heterogeneity occurs in thin phytoplankton layers (TPLs), where large numbers of photosynthetic microorganisms are found within a small depth interval. Some species of motile phytoplankton can form TPLs by gyrotactic trapping due to the interplay of their particular swimming style (directed motion biased against gravity) and the transport by a flow with shear along the direction of gravity. Here we consider gyrotactic swimmers in numerical simulations of the Kolmogorov shear flow, both in laminar and turbulent regimes. In the laminar case, we show that the swimmer motion is integrable and the formation of TPLs can be fully characterized by means of dynamical systems tools. We then study the effects of rotational Brownian motion or turbulent fluctuations (appearing when the Reynolds number is large enough) on TPLs. In both cases, we show that TPLs become transient, and we characterize their persistence.