Self-assembled rotating colloids in an active medium

Abstract

This work investigates the behavior of passive colloidal particles immersed in a chiral active fluid composed of ferromagnetic rotors subjected to a rotating magnetic field. Using numerical simulations, we study how the translational diffusion of passive particles is influenced by the spinning frequency of rotors, the vertical height above a no-slip boundary, and the emergent structural organization of the system. Our results show that the diffusion coefficient D of passive particles depends strongly on both the spinning frequency Λ and the height h: it increases linearly at short distances (h = 1), saturates at intermediate heights (h = 2), and exhibits a non-monotonic trend at larger separations (h = 5). We also analyze the radial distribution function to estimate the average cluster size ℓ, and find a strong linear correlation between ℓ and D, suggesting that collective organization enhances transport