Dynamics of a collection of active particles on a two-dimensional periodic undulated surface
Abstract
We study the dynamics of circular active particles (AP) on a two dimensional periodic undulated surface. Each particle has an internal energy mechanism which is modeled by an active friction force and it is controlled by an activity parameter v0. It acts as negative friction if the speed of the particle is smaller than v0 and normal friction otherwise. Surface undulation is modeled by the periodic undulation of fixed amplitude and wavelength and is measured in terms of a dimensionless ratio of amplitude and wavelength, h. The dynamics of the particle is studied for different activities, v0 and surface undulations (SU), h. Three types of particle dynamics are observed on varying activity and SU. For small v0 0.1 and h 0.8, particles remain confined in a surface minimum, for moderate v0 h, dynamics of particle shows an intermediate subdiffusion to late time diffusion and for large v0 h, it shows initial superdiffusion to late time diffusion. For all v0's and h 0.2, the dynamics of particle, satisfies the Green-Kubo relation between the effective diffusivity and velocity auto-correlation function. Systematic deviation is found on increasing h. Hence, an effective equilibrium can be established for a range of system parameters in this nonequilibirum system.