Influence of thermal fluctuations on active diffusion at large P\'{e}clet numbers
| Autor: | Dyer, Oliver T., Ball, Robin C. |
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| Rok vydání: | 2021 |
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| Zdroj: | Physics of Fluids, 33, 051904 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1063/5.0049386 |
| Popis: | Wavelet Monte Carlo dynamics simulations are used to study the dynamics of passive particles in the presence of microswimmers, taking account of the often-omitted thermal motion alongside the hydrodynamic flows generated by the swimmers. Although the P\'{e}clet numbers considered are large, we find the thermal motion to have a significant effect on the dynamics of our passive particles, and can be included as a decorrelation factor in the velocity autocorrelation with a decay time proportional to the P\'{e}clet number. Similar decorrelation factors come from swimmer rotations, e.g.~run and tumble motion, and apply to both entrainment and far field loop contributions. These decorrelation factors lead to active diffusivity having a weak apparent power law close to $Pe^{0.2}$ for small tracer-like particles at P\'{e}clet numbers appropriate for E. coli swimmers at room temperature. Meanwhile, the reduced hydrodynamic response of large particles to nearby forces has a corresponding reduction in active diffusivity in that regime. Together, they lead to a non-monotonic dependence of active diffusivity on particle size that can shed light on similar behaviour observed in experiments by Patteson et al. Comment: 33 pages, 8 figures. The following article has been submitted to the journal: Physics of Fluids. If/after it is published, it will be found at https://aip.scitation.org/journal/phf |
| Databáze: | arXiv |
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