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Updated: Jan 8, 2026
08:01
The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
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Nonmonotonic Diffusion in Sheared Active Suspensions of Squirmers
Zhouyang Ge1,2, John F Brady3, Gwynn J Elfring1
1University of British Columbia, Department of Mechanical Engineering and Institute of Applied Mathematics, Vancouver V6T 1Z4, British Columbia, Canada.
Physical Review Letters
|December 19, 2025
Summary
Shear flow surprisingly slows active particle diffusion in suspensions. This nonmonotonic diffusion arises from interactions between persistent motion and shear effects, offering new ways to control transport in active fluids.
Area of Science:
- Soft Matter Physics
- Fluid Dynamics
- Active Matter
Background:
- Active particles in suspensions exhibit complex dynamics influenced by internal propulsion and external forces.
- Understanding shear effects on active matter is crucial for applications in microfluidics and materials science.
Purpose of the Study:
- To investigate the influence of shear rate on the diffusive dynamics of active particles in suspensions.
- To elucidate the interplay between activity-induced motion and shear-induced effects on particle transport.
Main Methods:
- Utilizing apolar active suspensions of squirmers as model systems.
- Performing simulations of self-propelled particles with tunable persistence.
Main Results:
- Observed a nonmonotonic, slowing down of longtime diffusive dynamics with increasing shear rate.
- Demonstrated that this phenomenon arises from the coupling of persistent motion and shear-induced reorientation/diffusion.
- Confirmed the generality of nonmonotonic diffusion in active fluids with microstructure and persistence.
Conclusions:
- Shear exerts a nonlinear effect on diffusion in active suspensions.
- Internal activity and external forcing interact to modulate particle transport.
- Findings offer novel strategies for controlling transport phenomena in active fluids.
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