Active Turbulence in Shear Thinning Fluid

Fuente: arXiv
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Main Authors: Bian, Hongyi, Li, Chunhe, Lin, Zixiang, Zhu, Jin, Chen, Weijie, Li, Gaojin, Huang, Yongxiang, Qu, Zijie
Format: Preprint
Published: 2025
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_version_ 1866912681933406208
author Bian, Hongyi
Li, Chunhe
Lin, Zixiang
Zhu, Jin
Chen, Weijie
Li, Gaojin
Huang, Yongxiang
Qu, Zijie
author_facet Bian, Hongyi
Li, Chunhe
Lin, Zixiang
Zhu, Jin
Chen, Weijie
Li, Gaojin
Huang, Yongxiang
Qu, Zijie
contents The study of active matter system has critical importance in revealing the physical essence of biological collective behavior. Dense bacterial suspension - a typical biological active matter, exhibits a wide range of phenomenons, among which bacterial turbulence has received extensive interest in recent years. This seemingly chaotic motion is widely studied in Newtonian fluid. However, studies based on complex fluids have predominantly focused on viscoelastic effects, leaving the role of shear-thinning viscosity largely unexplored despite its prevalence in natural bacterial environments like mucus and gastric fluids. Here, we experimentally employed Ficoll and Methocel polymers to study the impacts of various viscosities by Newtonian fluid and shear-thinning effects by Non-Newtonian fluids on bacterial turbulence. We analyzed various physical properties, including energy, enstrophy, etc., and observed that the shear-thinning effect is significantly suppressed in high-concentration bacterial suspensions. While the ordered arrangement of polymer chains under shear flow leads to the microscopic anisotropic viscosity, the suppression is largely attributed to the disruption of polymer chains caused by strong inter bacterial interactions in dense suspensions. To validate this hypothesis, we conducted experiments at a lower bacterial concentration and verified the findings using theoretical calculations based on the modified Resistive Force Theory.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03638
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Active Turbulence in Shear Thinning Fluid
Bian, Hongyi
Li, Chunhe
Lin, Zixiang
Zhu, Jin
Chen, Weijie
Li, Gaojin
Huang, Yongxiang
Qu, Zijie
Soft Condensed Matter
Biological Physics
The study of active matter system has critical importance in revealing the physical essence of biological collective behavior. Dense bacterial suspension - a typical biological active matter, exhibits a wide range of phenomenons, among which bacterial turbulence has received extensive interest in recent years. This seemingly chaotic motion is widely studied in Newtonian fluid. However, studies based on complex fluids have predominantly focused on viscoelastic effects, leaving the role of shear-thinning viscosity largely unexplored despite its prevalence in natural bacterial environments like mucus and gastric fluids. Here, we experimentally employed Ficoll and Methocel polymers to study the impacts of various viscosities by Newtonian fluid and shear-thinning effects by Non-Newtonian fluids on bacterial turbulence. We analyzed various physical properties, including energy, enstrophy, etc., and observed that the shear-thinning effect is significantly suppressed in high-concentration bacterial suspensions. While the ordered arrangement of polymer chains under shear flow leads to the microscopic anisotropic viscosity, the suppression is largely attributed to the disruption of polymer chains caused by strong inter bacterial interactions in dense suspensions. To validate this hypothesis, we conducted experiments at a lower bacterial concentration and verified the findings using theoretical calculations based on the modified Resistive Force Theory.
title Active Turbulence in Shear Thinning Fluid
topic Soft Condensed Matter
Biological Physics
url https://arxiv.org/abs/2503.03638