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arXiv · 2608.05756

Near-field Hydrodynamics Disentangles Angular Correlations in Confined Active Suspensions

Changle Liao·Haruki Hayano·Yuto Uesugi·Akira Furukawa·Daiki Nishiguchi·Kazumasa A. Takeuchi
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Abstract

Spatial confinement profoundly impacts the transport and self-organization of active matter across diverse biological systems. While the collective orders in confined active matter have been extensively characterized, how geometric constraints reshape near-field flows and the resulting inter-particle correlations remains largely unexplored. In this study, we combine experiments and hydrodynamic simulations to investigate inter-particle correlations within quasi-two-dimensional Chlamydomonas reinhardtii suspensions. We reveal two disentangled modes characterizing cell pairs: a dipolar mode and an entrainment mode, which exhibit a density- and distance-dependent competition. Combining single-cell flow field analysis, hydrodynamic simulations, and active-passive mixtures, we link these two modes to singular hydrodynamics and lubrication-induced entrainment. Our results demonstrate that spatiotemporal correlations in confined active matter are fundamentally rooted in the interplay of these two hydrodynamic mechanisms.

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Changle Liao, Haruki Hayano, Yuto Uesugi, Akira Furukawa, Daiki Nishiguchi, Kazumasa A. Takeuchi. 2026-08-06. Near-field Hydrodynamics Disentangles Angular Correlations in Confined Active Suspensions. https://arxiv.org/abs/2608.05756

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