Aggregated self-propelled particles in microchannel-cavity structures

Collective motion of self-propelled particles can utilize their own energy to achieve non-equilibrium motion, exhibiting rich swimming behaviors and particle aggregation phenomena. This study numerically investigates the regulatory mechanisms of self-propelled type parameter (β), particle number (Num) on the capture efficiency, and aggregation coefficient of self-propelled particles within microchannel-cavity structures. The study shows that by increasing the value of |β|, the capture efficiency of self-propelled particles is decreased. By increasing the value of Num, the self-propelled particles with large |β| can be effectively captured, while the particles with small |β| have limited enhancement on capture efficiency. The pullers and pushers are more likely to adhere to the left wall corner and the right wall, respectively. The low pressure and high pressure areas in the left corner and right corner formed by the contraction and expansion structure of microchannel cavity, as well as the pressure distribution near the surface of the pusher and puller, are the main reasons for particle aggregation in different positions of the cavity. This research clarifies the collective motion of self-propelled particles under complex fluid environments.