Effect of speed fluctuations on the collective dynamics of active disks

Abstract

Numerical simulations are performed on the collective dynamics of active disks, whose self-propulsion speed ($U$) varies in time, and whose orientation evolves according to rotational Brownian motion. Two protocols for the evolution of speed are considered: (i) a deterministic one involving a periodic change in $U$ at a frequency $\omega$; and (ii) a stochastic one in which the speeds are drawn from a power-law distribution at time-intervals governed by a Poissonian process of rate $\beta$. In the first case, an increase in $\omega$ causes the disks to go from a clustered state to a homogeneous one through an apparent phase-transition, provided that the direction of self-propulsion is allowed to reverse. Similarly, in the second case, for a fixed value of $\beta$, the extent of cluster-breakup is larger when reversals in the self-propulsion direction are permitted. Motility-induced phase separation of the disks may therefore be avoided in active matter suspensions in which the constituents are allowed to reverse their self-propulsion direction, immaterial of the precise temporal nature of the reversal (deterministic or stochastic). Equally, our results demonstrate that phase separation could occur even in the absence of a time-averaged motility of an individual active agent, provided that the rate of direction reversals is smaller than the orientational diffusion rate.

13 pages, 14 figures, 8 supplementary videos

References in corpus (12)

• Motility-Induced Phase Separation
• Self-propulsion of pure water droplets by spontaneous Marangoni stress driven motion
• Active colloidal suspensions: Clustering and phase behavior
• Self-propelled particles with fluctuating speed and direction of motion
• Motility-Induced Microphase and Macrophase Separation in a Two-Dimensional Active Brownian Particle System
• Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles
• Clustering and flocking of repulsive chiral active particles with non-reciprocal couplings
• Dynamical Clustering Interrupts Motility Induced Phase Separation in Chiral Active Brownian Particles
• Kinetics of motility-induced phase separation and swim pressure
• Tuning Nonequilibrium Phase Transitions with Inertia
• The bouncing dynamics of inertial self-propelled particles reveals directional asymmetry
• Non-Brownian diffusion and chaotic rheology of autophoretic disks

Cited by in corpus (1)

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