We study the orientation statistics of spheroidal, axisymmetric microswimmers, with shapes ranging from disks to rods, swimming in chaotic, moderately turbulent flows. Numerical simulations show that rodlike active particles preferentially align with the flow velocity. To explain the underlying mechanism, we solve a statistical model via the perturbation theory. We show that such an alignment is caused by correlations of fluid velocity and its gradients along particle paths combined with fore-aft symmetry breaking due to both swimming and particle nonsphericity. Remarkably, the discovered alignment is found to be a robust kinematical effect, independent of the underlying flow evolution. We discuss its possible relevance for aquatic ecology.

Alignment of Nonspherical Active Particles in Chaotic Flows

Borgnino M.;De Lillo F.;Boffetta G.;
2019-01-01

Abstract

We study the orientation statistics of spheroidal, axisymmetric microswimmers, with shapes ranging from disks to rods, swimming in chaotic, moderately turbulent flows. Numerical simulations show that rodlike active particles preferentially align with the flow velocity. To explain the underlying mechanism, we solve a statistical model via the perturbation theory. We show that such an alignment is caused by correlations of fluid velocity and its gradients along particle paths combined with fore-aft symmetry breaking due to both swimming and particle nonsphericity. Remarkably, the discovered alignment is found to be a robust kinematical effect, independent of the underlying flow evolution. We discuss its possible relevance for aquatic ecology.
2019
123
13
138003-1
138003-6
http://harvest.aps.org/bagit/articles/10.1103/PhysRevLett.123.138003/apsxml
https://arxiv.org/abs/1909.02458
Bacterial Physiological Phenomena; Biomechanical Phenomena; Hydrodynamics; Models, Biological; Motion; Swimming; Models, Theoretical
Borgnino M.; Gustavsson K.; De Lillo F.; Boffetta G.; Cencini M.; Mehlig B.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1728251
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