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A computational study of surface accumulation and exploration of chiral active particles
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Resumo(s)
Biological and man-made active particles (microswimmers when hydrodynamics are considered) often move in complex crowded environments where they encounter boundaries such as surfaces or obstacles. Recently it was shown experimentally that the interaction of active particles with boundaries is determined primarily by steric forces and short-ranged hydrodynamics.
In the first chapter of this thesis, we consider solely steric interactions and study numerically the role of disorder in the transport dynamics of chiral active particles on surfaces with obstacles. We consider different densities of regularly spaced obstacles and distinct types of disorder: noise in the dynamics of the particle, quenched noise in the positions of the obstacles as well as obstacle size polydispersity. We show that, depending on the type and strength of the disorder, the presence of obstacles can either enhance or hinder mass transport. In the second chapter, we introduce a three-dimensional model of a microswimmer, where we include hydrodynamics in an effective way, navigating a volume bounded by a top and bottom surface. We describe the swimmer-surface interaction with an effective short-ranged hydrodynamic alignment force, and study numerically the effect of surface texture, modelled by obstacles, on the surface accumulation of chiral and non-chiral microswimmers. We find that, depending on the angular velocity of the swimmer, and the alignment force, obstacles can either hinder or enhance surface accumulation. We discuss potential applications to sorting of microswimmers by their angular velocity.
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Palavras-chave
chiral active particles disorder in transport dynamics obstacles and surface structure 3D model of a microswimmer surface accumulation of bacteria partículas ativas quirais desordem na dinâmica de transporte obstáculos e estrutura de superfície modelo 3D de um micropropulsor acumulação de bactérias na superfície