Abstract
Small heavy particles in a fluid flow respond to the flow on a timescale proportional to their inertia or Stokes number . Their behavior has been thought to be gradually modified as increases. We show, on the other hand, in the steady spatially periodic laminar Taylor-Green vortex flow, that particle dynamics, and their effective diffusivity, actually change in an irregular, nonmonotonic, and sometimes discontinuous manner with increasing . At , we show chaotic particle motion, contrasting with earlier conclusions for heavy particles in the same flow [Wang et al., Phys. Fluids 4, 1789 (1992)]. Particles may display trapped orbits, or unbounded diffusive or ballistic dispersion, with the vortices behaving like scatterers in a soft Lorentz gas [Klages et al., Phys. Rev. Lett. 122, 064102 (2019)]. The dynamics is nonergodic.
6 More- Received 19 April 2023
- Accepted 8 December 2023
DOI:https://doi.org/10.1103/PhysRevFluids.9.014302
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