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Anomalous Cooling and Overcooling of Active Colloids
Fabian Jan Schwarzendahl1, Hartmut Löwen1
1Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
Physical Review Letters
|October 7, 2022
Summary
Active colloids exhibit the Mpemba effect, cooling faster at higher temperatures. This activity also leads to surprising "activity-induced overcooling," where temperatures drop below the final equilibrium.
Area of Science:
- Physics
- Colloid Science
- Active Matter
Background:
- The Mpemba effect describes faster cooling of hotter systems.
- This phenomenon has been observed in trapped colloids.
- Active colloids are systems with self-propulsion.
Purpose of the Study:
- Investigate the Mpemba effect in active colloids.
- Explore cooling and heating dynamics of self-propelled particles.
- Develop a testable model for active colloid behavior.
Main Methods:
- Numerical simulations of active colloids.
- Theoretical calculations.
- Modeling of active particle dynamics.
Main Results:
- Activity induces the Mpemba effect during cooling.
- Active particles temporarily deviate from effective temperature descriptions.
- Activity-induced overcooling observed, reaching temperatures below equilibrium.
Conclusions:
- Self-propelled active colloids display the Mpemba effect.
- Activity influences cooling dynamics and temperature descriptions.
- Activity-induced overcooling is a novel phenomenon in active matter systems.
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