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Main Authors: Palmer, Bryce, Weady, Scott, O'Brien, Michael, Burkhart, Blakesley, Shelley, Michael J.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.18299
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author Palmer, Bryce
Weady, Scott
O'Brien, Michael
Burkhart, Blakesley
Shelley, Michael J.
author_facet Palmer, Bryce
Weady, Scott
O'Brien, Michael
Burkhart, Blakesley
Shelley, Michael J.
contents Suspensions of swimming particles exhibit complex collective behaviors driven by hydrodynamic interactions, showing persistent large-scale flows and long-range correlations. While heavily studied, it remains unclear how such structures depend on the system size and swimmer concentration. To address these issues, we simulate very large systems of suspended swimmers across a range of system sizes and volume fractions. For this we use high-performance simulation tools that build on slender body theory and implicit resolution of steric interactions. At low volume fractions and long times, the particle simulations reveal dynamic flow structures and correlation functions that scale with the system size. These results are consistent with a mean-field limit and agree well with a corresponding kinetic theory. At higher concentrations, the system departs from mean-field behavior. Flow structures become cellular, and correlation lengths scale with the particle size. Here, translational motion is suppressed, while rotational dynamics dominate. These findings highlight the limitations of dilute mean-field models and reveal new behaviors in dense active suspensions.
format Preprint
id arxiv_https___arxiv_org_abs_2505_18299
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Correlations, mean-field limits, and transition to the concentrated regime in motile particle suspensions
Palmer, Bryce
Weady, Scott
O'Brien, Michael
Burkhart, Blakesley
Shelley, Michael J.
Soft Condensed Matter
Suspensions of swimming particles exhibit complex collective behaviors driven by hydrodynamic interactions, showing persistent large-scale flows and long-range correlations. While heavily studied, it remains unclear how such structures depend on the system size and swimmer concentration. To address these issues, we simulate very large systems of suspended swimmers across a range of system sizes and volume fractions. For this we use high-performance simulation tools that build on slender body theory and implicit resolution of steric interactions. At low volume fractions and long times, the particle simulations reveal dynamic flow structures and correlation functions that scale with the system size. These results are consistent with a mean-field limit and agree well with a corresponding kinetic theory. At higher concentrations, the system departs from mean-field behavior. Flow structures become cellular, and correlation lengths scale with the particle size. Here, translational motion is suppressed, while rotational dynamics dominate. These findings highlight the limitations of dilute mean-field models and reveal new behaviors in dense active suspensions.
title Correlations, mean-field limits, and transition to the concentrated regime in motile particle suspensions
topic Soft Condensed Matter
url https://arxiv.org/abs/2505.18299