Lauga_et_al-2017-Europhysics_Letters-AM.pdf (1.21 MB)
Clustering instability of focused swimmers
journal contribution
posted on 2018-08-30, 11:03 authored by Eric Jean-Marie Lauga, Francois NadalOne of the hallmarks of active matter is its rich nonlinear dynamics and instabilities. Recent numerical simulations of phototactic algae showed that a thin jet of swimmers, obtained from hydrodynamic focusing inside a Poiseuille flow, was unstable to longitudinal perturbations with swimmers dynamically clustering (Jibuti L. et al., Phys. Rev. E, 90, (2014) 063019). As a simple starting point to understand these instabilities, we consider in this paper an initially homogeneous one-dimensional line of aligned swimmers moving along the same direction, and characterise its instability using both a continuum framework and a discrete approach. In both cases, we show that hydrodynamic interactions between the swimmers lead to instabilities in density for which we compute the growth rate analytically. Lines of pusher-type swimmers are predicted to remain stable while lines of pullers (such as flagellated algae) are predicted to always be unstable.
Funding
This work was funded in part by the European Union through a Marie Curie CIG Grant and an ERC consolidator grant to EL.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Published in
EPLVolume
116Issue
6Citation
LAUGA, E. and NADAL, F., 2017. Clustering instability of focused swimmers. EPL, 116 (6), 64004, doi: 10.1209/0295-5075/116/64004Publisher
IOP Publishing © EPLAVersion
- AM (Accepted Manuscript)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Acceptance date
2017-01-18Publication date
2017-02-09Copyright date
2016Notes
This article was published in the EPL Journal [©EPLA] and the definitive version is available at: https://doi.org/10.1209/0295-5075/116/64004ISSN
0295-5075eISSN
1286-4854Publisher version
Language
- en