Ratchet effect and jamming in dense mixtures of active and passive colloids in narrow pores

Fuente: arXiv
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Autores principales: Slanina, Frantisek, Kotrla, Miroslav
Formato: Preprint
Publicado: 2025
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author Slanina, Frantisek
Kotrla, Miroslav
author_facet Slanina, Frantisek
Kotrla, Miroslav
contents Using the framework of generalized exclusion processes we study mixtures of passive and active particles interacting by steric repulsion. The particles move in a pore with periodically modulated aperture, which is modeled by a quasi-one-dimensional channel with periodic tooth-shaped profile. Internal driving of the active particles induces a ratchet current of these particles. In the current-density diagram, we observe three main regimes: of free flow; of thermally activated processes; of spinodal decomposition. When the density of particles is increased, we observe a transition to jammed state, where the ratchet current is substantially reduced. In time evolution, the transition to jammed state is seen as sudden drop of current at certain time. The probability distribution of these jamming times follows an exponential law. The average jamming time depends itself exponentially on the density of active particles. The coefficient in this exponential is nearly independent of the switching rate of the active particles as well as on the presence or absence of passive particles. Due to the interaction, the current of active particles imposes a drag on the passive particles. In the limit of both large systems and long times, the current of passive particles has always the same direction as the ratchet current of active particles. However, during the evolution of the system we observe very slow (logarithmic in time) approach to the asymptotic value, sometimes accompanied by current reversal, i.e. current of active and passive particles may go in opposite direction.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09672
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ratchet effect and jamming in dense mixtures of active and passive colloids in narrow pores
Slanina, Frantisek
Kotrla, Miroslav
Statistical Mechanics
Soft Condensed Matter
Using the framework of generalized exclusion processes we study mixtures of passive and active particles interacting by steric repulsion. The particles move in a pore with periodically modulated aperture, which is modeled by a quasi-one-dimensional channel with periodic tooth-shaped profile. Internal driving of the active particles induces a ratchet current of these particles. In the current-density diagram, we observe three main regimes: of free flow; of thermally activated processes; of spinodal decomposition. When the density of particles is increased, we observe a transition to jammed state, where the ratchet current is substantially reduced. In time evolution, the transition to jammed state is seen as sudden drop of current at certain time. The probability distribution of these jamming times follows an exponential law. The average jamming time depends itself exponentially on the density of active particles. The coefficient in this exponential is nearly independent of the switching rate of the active particles as well as on the presence or absence of passive particles. Due to the interaction, the current of active particles imposes a drag on the passive particles. In the limit of both large systems and long times, the current of passive particles has always the same direction as the ratchet current of active particles. However, during the evolution of the system we observe very slow (logarithmic in time) approach to the asymptotic value, sometimes accompanied by current reversal, i.e. current of active and passive particles may go in opposite direction.
title Ratchet effect and jamming in dense mixtures of active and passive colloids in narrow pores
topic Statistical Mechanics
Soft Condensed Matter
url https://arxiv.org/abs/2508.09672