Gyrotactic trapping in laminar and turbulent Kolmogorov flow

Abstract

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.

arXiv comment12 pages, 12 figures

References in corpus (7)

• Fluid dynamics of bacterial turbulence
• Nonlinear dynamics of a microswimmer in Poiseuille flow
• Periodic and Quasiperiodic Motion of an Elongated Microswimmer in Poiseuille Flow
• Light control of the flow of phototactic microswimmer suspensions
• Turbulent fluid acceleration generates clusters of gyrotactic microorganisms
• Stochastic dynamics of active swimmers in linear flows
• Turbulent channel without boundaries: The periodic Kolmogorov flow

Cited by in corpus (20)

• Emergent behavior in active colloids
• Flow Navigation by Smart Microswimmers via Reinforcement Learning
• Finding Efficient Swimming Strategies in a Three Dimensional Chaotic Flow by Reinforcement Learning
• Preferential sampling and small-scale clustering of gyrotactic microswimmers in turbulence
• Gyrotactic swimmers in turbulence: shape effects and role of the large-scale flow
• Photofocusing: Light and flow of phototactic microswimmer suspension
• Jeffery's orbits and microswimmers in flows: A theoretical review
• Gyrotactic phytoplankton in laminar and turbulent flows: a dynamical systems approach
• Swimming strategy of settling elongated microswimmers by reinforcement learning
• Dynamics of a long chain in turbulent flows: Impact of vortices
• Microswimmers in an axisymmetric vortex flow
• Turbulence induces clustering and segregation of non-motile, buoyancy-regulating phytoplankton
• Reaching for the surface: Spheroidal microswimmers in surface gravity waves
• Swimmer dynamics in externally-driven fluid flows: The role of noise
• Alignment of elongated swimmers in a laminar and turbulent Kolmogorov flow
• The instability of gyrotactically-trapped cell layers
• Noise-induced aggregation of swimmers in the Kolmogorov flow
• Scale-dependent co-localization in a population of gyrotactic swimmers
• Active gyrotactic stability of microswimmers using hydromechanical signals
• Orientation Dynamics of Gyrotactic Microswimmers in Turbulent Flows