Is the active suspension in a complex viscoelastic fluid more chaotic or more ordered?

Fuente: arXiv
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Main Authors: Zhou, Yuan, Zou, Qingzhi, Pagonabarraga, Ignacio, Zhang, Kaihuan, Qi, Kai
Format: Preprint
Published: 2025
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author Zhou, Yuan
Zou, Qingzhi
Pagonabarraga, Ignacio
Zhang, Kaihuan
Qi, Kai
author_facet Zhou, Yuan
Zou, Qingzhi
Pagonabarraga, Ignacio
Zhang, Kaihuan
Qi, Kai
contents The habitat of microorganisms is typically complex and viscoelastic. A natural question arises: Do polymers in a suspension of active swimmers enhance chaotic motion or promote orientational order? We address this issue by performing lattice Boltzmann simulations of squirmer suspensions in polymer solutions. At intermediate swimmer volume fractions, comparing to the Newtonian counterpart, polymers enhance polarization by up to a factor of 26 for neutral squirmers and 5 for pullers, thereby notably increasing orientational order. This effect arises from hydrodynamic feedback mechanism: squirmers stretch and align polymers, which in turn reinforce swimmer orientation and enhance polarization via hydrodynamic and steric interactions. The mechanism is validated by a positive correlation between polarization and a defined polymer-swimmer alignment parameter. Our findings establish a framework for understanding collective motion in complex fluids and suggest strategies for controlling active systems via polymer-mediated interactions.
format Preprint
id arxiv_https___arxiv_org_abs_2512_18580
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Is the active suspension in a complex viscoelastic fluid more chaotic or more ordered?
Zhou, Yuan
Zou, Qingzhi
Pagonabarraga, Ignacio
Zhang, Kaihuan
Qi, Kai
Soft Condensed Matter
Biological Physics
Computational Physics
Fluid Dynamics
The habitat of microorganisms is typically complex and viscoelastic. A natural question arises: Do polymers in a suspension of active swimmers enhance chaotic motion or promote orientational order? We address this issue by performing lattice Boltzmann simulations of squirmer suspensions in polymer solutions. At intermediate swimmer volume fractions, comparing to the Newtonian counterpart, polymers enhance polarization by up to a factor of 26 for neutral squirmers and 5 for pullers, thereby notably increasing orientational order. This effect arises from hydrodynamic feedback mechanism: squirmers stretch and align polymers, which in turn reinforce swimmer orientation and enhance polarization via hydrodynamic and steric interactions. The mechanism is validated by a positive correlation between polarization and a defined polymer-swimmer alignment parameter. Our findings establish a framework for understanding collective motion in complex fluids and suggest strategies for controlling active systems via polymer-mediated interactions.
title Is the active suspension in a complex viscoelastic fluid more chaotic or more ordered?
topic Soft Condensed Matter
Biological Physics
Computational Physics
Fluid Dynamics
url https://arxiv.org/abs/2512.18580