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Capillary Action in Scalar Active Matter
1Department of Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken 66123, Germany.
Physical Review Letters
|February 15, 2020
Summary
Active matter exhibits capillary action, rising in tubes and wetting surfaces due to emergent attraction. This phenomenon is quantified by the active sedimentation length, impacting porous media and suspensions.
Area of Science:
- Physics
- Soft Matter Physics
- Colloidal Science
Background:
- Capillary action in classical fluids arises from intermolecular attractions.
- Active matter, like colloids or bacteria, exhibits self-propulsion and unique collective behaviors.
- Understanding active matter's interaction with surfaces and porous media is crucial for various applications.
Purpose of the Study:
- To investigate capillary rise and wetting phenomena in active matter systems.
- To explore capillarity in a minimal model of scalar active matter with repulsive interactions.
- To quantify the relationship between capillary phenomena and the active sedimentation length.
Main Methods:
- Utilizing simulations of a minimal model for scalar active matter.
- Analyzing capillary rise in thin tubes.
- Studying wetting of vertical plates.
- Investigating spontaneous imbibition in disordered porous media.
Main Results:
- An effective attraction emerges in active matter with purely repulsive interactions due to particle collisions.
- Capillary rise in thin tubes is proportional to the active sedimentation length (λ).
- Wetting height on vertical plates scales superlinearly with λ.
- Imbibition height in porous media scales as ⟨h⟩∝λϕ_{m}.
Conclusions:
- Active matter can exhibit capillarity through emergent attractive forces.
- The active sedimentation length is a key parameter governing capillary phenomena in active matter.
- These findings are relevant for suspensions of active colloids and bacteria in porous environments.
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