Simulation of Passive Particles Diffusion Behavior in Active Fluids

By extending Langevin equation to simulate the motion of active particles, a blend system of passive particles and active particles was established to study the diffusion behavior of passive particles in active fluids. The diffusion coefficient is determined by calculating the mean square displacement of the passive particles. Effect of active particle concentration, self-propelling speed and passive particle size on the diffusion behavior of passive particle is investigated. The results show that the diffusion coefficient of passive particles in active fluids decreases with the increase of their own particle size. The diffusion of passive particles can be significantly enhanced by increasing the concentration and self-propelling speed of active particles. The diffusion behavior of passive particles immersed in the active fluid behaves as sub-diffusion in the initial stage, and then transforms into super-diffusion. The effective temperature of active fluid system increases with the increase of active fluid concentration and the passive particle size, which is equivalent to the passive particles being immersed in a higher temperature fluid. © 2022, Science Press. All right reserved.