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Self-propulsion against a moving membrane: Enhanced accumulation and drag force
U Marini Bettolo Marconi1, A Sarracino2, C Maggi3
1Scuola di Scienze e Tecnologie, Università di Camerino, Via Madonna delle Carceri, 62032, Camerino, INFN Perugia, Italy.
Physical Review. E
|January 20, 2018
Summary
Active particles (AP) interacting with a moving membrane show enhanced accumulation and drag. This self-propulsion effect, driven by membrane velocity, can be used for filtering AP.
Area of Science:
- Soft Matter Physics
- Active Matter
- Colloidal Science
Background:
- Active particles (AP) exhibit self-propulsion (SP), differentiating them from passive colloids.
- SP leads to accumulation at static interfaces, even without hydrodynamic interactions.
Purpose of the Study:
- To investigate the role of SP in the interaction between AP and a moving semipermeable membrane.
- To model the behavior of noninteracting AP in a channel with a moving, partially penetrable wall.
Main Methods:
- Implementation of a computational model for noninteracting AP.
- Simulation of AP interacting with a partially penetrable wall moving at a constant velocity (c).
- Development of an approximate analytical scheme to analyze particle density profiles and drag force.
Main Results:
- AP with finite membrane velocity (c) show enhanced accumulation in front of the moving membrane compared to passive colloids or AP with c=0.
- A significantly increased drag force is experienced by AP interacting with the moving membrane.
- An effective potential at the interface, proportional to cτ/ξ, explains the observed phenomena.
Conclusions:
- Self-propulsion significantly alters AP interactions with moving interfaces, leading to enhanced accumulation and drag.
- The findings are supported by strong agreement between analytical predictions and numerical simulations.
- This research offers potential applications for the automatic selection and filtering of active particles based on their parameters.
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