Dynamic Behavior Of Rod-coil Like Swimmer

In recent years active matter is an important research field in soft matter.Thanks to advances in experimental technology,various kinds of artificial active substance are prepared in the laboratory.This also provides a platform for the systematic study of the dynamic behavior of the active material.This article use the method of dissipative particle dynamic to study dynamic behavior of a single swimmer similar to rod-coil in twodimensional periodic boundary.The magnitude and direction of the active force,the longitudinal ratio of chain and rod,and the damping intensity of solution are important parameters that affects its dynamic behavior.The research contents of this paper mainly include the following two parts:(1)Rod is active units of swimmer,its driving direction is to point along the rod to the non-grafting end.We systematically studied the influence of the active force、the length of rod and chain and damping friction coefficient on swimmer dynamic behavior.The results shows that with the increase of active force,the diffusion rate of the swimmer in the system is also increasing.Increasing the length of rod is also speeding up the diffusion of swimmer.We find that the diffusion coefficient of swimmer is only small change if we increase the length of the chain,but its persistence in moving direction is increasing.(2)In this case,the driving direction of rod is to point along the rod to the grafting end.We find that as the active force increased,the swimmer gradually changed from the random movements to the periodic motion,and the period is reduced.The length of rod has a great influence on whether swimmer has a periodic motion.As the length of rod increases,the swimmer turns from a random rotation to a directional rotation.and its gradually becomes periodic.The length of chain also has a certain effect on whether swimmer has a periodic motion.The size of damping also affects the directional rotation of swimmer.when damping is small,swimmer makes directional rotation.When the damping increasing to a certain extent,it will destroy the directional rotation of the swimmer.