Escape dynamics of active Janus particle from porous circular cavity

Janus particle is nano to micro meter sized entity having two distinct faces, only one of which is chemically or physically active. A class of Janus particle is called self-propelled or active Janus which can move extracting energy from environment by creating concentration or thermal gradient at the vicinity of its active surface. We numerically study the mean exit time of active particle of the Janus kind from a circular cavity with single or multiple exit windows. Our simulation results witness distinct escape mechanisms depending upon the relative amplitudes of the thermal length and self-propulsion length compared to the cavity and pore sizes. For exceedingly large self-propulsion lengths, overdamped active particles diffuse on the cavity surface, and rotational dynamics solely governs the exit process. On the other hand, the escape kinetics of a very weakly damped active particle is largely dictated by bouncing effects on the cavity walls irrespective of the amplitude of self-propulsion persistent lengths. We show that the exit rate can be maximized for an optimal self-propulsion persistence length, which depends on the damping strength, self-propulsion velocity, and cavity size. However, the optimal persistence length is insensitive to the opening windows' size, number, and arrangement. The present analysis aims to understand the transport controlling mechanism of active matter in confined structures. The findings of this study can be used in medical science and nano technology.