title: Diffusion, subdiffusion, and trapping of active particles in heterogeneous media.
abstract: We study the transport properties of a system of active particles moving at constant speed in a heterogeneous two-dimensional space. The spatial heterogeneity is modeled by a random distribution of obstacles, which the active particles avoid. Obstacle avoidance is characterized by the particle turning speed γ. We show, through simulations and analytical calculations, that the mean square displacement of particles exhibits two regimes as function of the density of obstacles ρ(o) and γ. We find that at low values of γ, particle motion is diffusive and characterized by a diffusion coefficient that displays a minimum at an intermediate obstacle density ρ(o). We observe that in high obstacle density regions and for large γ values, spontaneous trapping of active particles occurs. We show that such trapping leads to genuine subdiffusive motion of the active particles. We indicate how these findings can be used to fabricate a filter of active particles.
authors.affiliation: Department for Theoretical Physics, Odessa National University, Dvoryanskaya 2, 65026 Odessa, Ukraine and Laboratoire J.A. Dieudonné, UMR 7351 CNRS, Université Nice Sophia Antipolis, Parc Valrose, F-06108 Nice Cedex 02, France.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Chepizhko
authors.forename: Fernando
authors.initials: F
authors.lastname: Peruani