| The nonequilibrium clustering of active particles around the obstacle in two dimensions is investigated using Brownian dynamics simulations.A typical V-shaped obstacle and the obstacle with different shapes are considered.For the V-shaped obstacle,the capture rate P of active particles by the obstacle and the effective force F of active particles on the obstacle can be effectively controlled by varying the apex angleθand particle densityρ.A capture“phase diagram”indicates that the critical apex angleθ~*and particle densityρ~*correspond to the optimal capture state.In contrast with the V-shaped obstacle,the Semi-arc obstacle exhibits a poor capability to capture active particles.Meanwhile,the Unclosed-rectangle obstacle demonstrates a stronger capturing capability regardless of the inner area,which suggests the significance of the apex angle for the clustering of active particles.Changing the central angle corresponding to the arc-shaped obstacle increases the number of active particles accumulated in the interior,and the capture rate increases stepwise,but the method of clustering of the active particles in the interior is different from that of other obstacles.Further considering the case that the V-shaped obstacle with two apex angles existing at the same time,compared with the one obstacle with a larger angle,the other obstacle with a smaller angle first achieves captured saturation.Then,the angle of the obstacle,the density of the active particles,and the relationship between the internal area of the obstacle and the orderly arrangement of the active particles are considered respectively.By changing the size of the included angle of the obstacle and the area inside the obstacle,the order of the active particles arranged inside the obstacle can be changed,and the order of the active particles under different included angles varies with density.These results can provide insight into the clustering behavior of active particles in a crowded and complex environment and help in designing effective trapping devices. |
