STUDY ON TRANSPORT OF ACTIVE PARTICLES IN POISEUILLE FLOW NEAR WALL

Mastering the migration principle of active particles under shear flow is of great significance for realizing particle separation and process intensification. Based on the theory of dissipative particle dynamics, a mathematical model describing the migration of active particles in Poiseuille flow near wall in microchannels is established. The effects of the circular angular velocity, chirality-induced angular velocity, self-propulsion velocity and rotational diffusion coefficient on the lateral migration velocity and forced tumble frequency of Escherichia coli and conventional active particles are investigated. Meanwhile, the formation mechanism of the lateral migration of active particles in the shear flow near wall is determined. The results show that the lateral migration velocity of Escherichia coli in the shear flow near wall increases rapidly at first and then stabilizes with the increase of shear rate. The lateral migration velocity of the Escherichia coli decreases with the increase of circular angular velocity, and increases with the increase of chirality-induced angular velocity, self-propulsion velocity and rotational diffusion coefficient. The forced tumble frequency of Escherichia coli is less affected by the circular angular velocity, self-propulsion velocity and rotational diffusion coefficient but increases with the increase of the chirality-induced angular velocity. In contrast with the Escherichia coli, the lateral migration velocity of the conventional active particles is significantly reduced, and the forced tumble frequency is significantly slower. Both the lateral migration velocity and the forced tumble frequency of the conventional active particles are affected by the self-propulsion velocity and rotational diffusion coefficient in a similar way to that of Escherichia coli. The forward locomotion is the precondition for the formation of lateral migration of active particles, while other kinematic parameters and structural parameters can have promotion or inhibition effect on the lateral migration of active particles under shear flow near wall to some extent.