2019/09/05 by M. Borgnino, K. Gustavsson, F. De Lillo +3 · 1 citation
Physics and Astronomy · #physics.flu-dyn #cond-mat.soft
paper · pdf · doi:10.1103/physrevlett.123.138003
published as Phys. Rev. Lett. 123, 138003 (2019) · 5 pages, 3 figures, Supplements in Ancillary directory, accepted in Physical Review Letters
arxiv created 2019/09/05 · arxiv updated 2019/10/02
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 rod-like active particles preferentially align with the flow velocity. To explain the underlying mechanism we solve a statistical model via perturbation theory. We show that such 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.