Berlin 2024 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 2: Active Matter I (joint session BP/CPP/DY)
DY 2.5: Talk
Monday, March 18, 2024, 10:30–10:45, H 1028
Dynamics and phase separation of active Brownian particles on curved surfaces and in porous media — •Priyanka Iyer, Roland Winkler, Dmitry Fedosov, and Gerhard Gompper — Theoretical Physics of Living Matter (IBI-5/IAS-2), Forschungszentrum Jülich
In biophysical systems, active particles are often exposed to curved geometries and confinement. This prompts a crucial question: How does curvature influence the emergent collective behavior of active particles? We study this question by considering the effect of curvature on an ensemble of repulsive active Brownian particles (ABPs) moving on a spherical surface. Surface curvature affects the dynamics of ABPs, as it introduces a new time scale τ = R/v0, with curvature radius R and propulsion velocity v0, in addition to the rotational diffusion time τr. The time scale τ is related to a stop-and-go motion caused by the recurrent alignment of the propulsion direction with the surface normal. This implies that motility-induced phase separation (MIPS) disappears for large curvature. Moreover, the phase-separation boundary at low area fraction φ attains a turning point for small R, allowing for the possibility of a re-entrant behavior. The findings also have implications for understanding how curvature influences ABP dynamics in porous media, as demonstrated through a paradigmatic example involving two connected pores. Surprisingly, it is found that the different curvatures of the two pores can facilitate particle flux towards regions of high particle density and induce transient MIPS states.
[1] Iyer et al. Phys. Rev. Res. 5, 033054 (2023).
Keywords: Active Brownian Particles; Dry Active Matter; Phase Separation; Porous Media; Statistical Physics