Naveen Kumar Agrawal


MS Student

 Active-Passive Particle System: Collective behavior in phase transition and phase separation

In nature, we witness fascinating scenes of patterns formed by flocking of bees, ants, and crowds. These patterns are ubiquitous across the length scales from micro to meters, living to non-living. These patterns are formed because of collective behavior between the constituents: active and passive particles. The former is self-capable of producing persistent motion, whereas the latter is not capable of doing so. There are various force interactions involved in such systems. The dominance of one over the other results in the formulation of different collective patterns, also called phases. We study the formation of a collective vortex called Mill. A DEM-based model is used in a binary active-passive system. The competition between the self-propulsion and alignment interaction resulted in a first-order phase transition. The effects of intrinsic noise on the collective mill formation are explored using various order parameters. One exciting and practical importance of the observed collective behavior is the formation of phase-separated regions observed. Here the active and passive particles get separated into aggregates of identical particles, as shown in the figure.




  • Naveen Kumar Agrawal, Pallab Sinha Mahapatra, “Effect of particle fraction on phase transitions in an active-passive particles system”, Physical Review E, 101(4):042607, 2020.

 Book Chapter:

  • Naveen Kumar Agrawal, Pallab Sinha Mahapatra, Tuhin Subhra Santra, “Micro-Robots/Swimmers For Bio-Medical Applications” In: Microfluidics And Bio-MEMS: Devices And Applications, PAN Stanford Publication. (In press)


  • Naveen Kumar Agrawal, Pallab Sinha Mahapatra, “Phase transitions in the system of active and passive microswimmers”, Bulletin of the American Physical Society, 23-26 November 2019, Seattle, USA
  • Naveen Kumar Agrawal, Pallab Sinha Mahapatra, “Collective behavior and motility induced segregation in an active-passive particle system”, Motile Active Matter, 26-29 October 2020, Bonn, Germany (Accepted)

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