Inertial Self-Caging: Dynamics of Macroscopic Swimmers at Moderate Reynolds Number Sustaining Chemical Wake Resonance

Fuente: arXiv
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Main Authors: Foradori, Alessandro, Bettotti, Paolo
Format: Preprint
Published: 2026
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author Foradori, Alessandro
Bettotti, Paolo
author_facet Foradori, Alessandro
Bettotti, Paolo
contents Self-propelled phoretic swimmers are generally studied in the laminar flow regime, where their low speed renders inertial effects negligible and trajectories highly predictable. This research tackles the challenge of propulsion in the inertial regime, at moderate Reynolds numbers (100 < Re < 200), where fluid dynamics becomes non-linear. By using a chemically driven macroscopic hydrogel this work demonstrates, through experiments and modeling, the existence of stable resonant states under confined geometry: as the swimmer circles, it interacts with its own lasting chemical wake. This chemical self-feedback creates a complex, stable motion characterized by both universal exponential speed decay with superimposed significant periodic speed oscillations. Furthermore, a critical threshold speed is identified, where the system abruptly transitions from the resonant oscillatory regime to a stochastic stop & go behavior. These findings provide a fundamental understanding of how chemical fields, hydrodynamic inertia, and confinement couple to determine the motion properties of high-speed active matter.
format Preprint
id arxiv_https___arxiv_org_abs_2601_11264
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Inertial Self-Caging: Dynamics of Macroscopic Swimmers at Moderate Reynolds Number Sustaining Chemical Wake Resonance
Foradori, Alessandro
Bettotti, Paolo
Fluid Dynamics
Self-propelled phoretic swimmers are generally studied in the laminar flow regime, where their low speed renders inertial effects negligible and trajectories highly predictable. This research tackles the challenge of propulsion in the inertial regime, at moderate Reynolds numbers (100 < Re < 200), where fluid dynamics becomes non-linear. By using a chemically driven macroscopic hydrogel this work demonstrates, through experiments and modeling, the existence of stable resonant states under confined geometry: as the swimmer circles, it interacts with its own lasting chemical wake. This chemical self-feedback creates a complex, stable motion characterized by both universal exponential speed decay with superimposed significant periodic speed oscillations. Furthermore, a critical threshold speed is identified, where the system abruptly transitions from the resonant oscillatory regime to a stochastic stop & go behavior. These findings provide a fundamental understanding of how chemical fields, hydrodynamic inertia, and confinement couple to determine the motion properties of high-speed active matter.
title Inertial Self-Caging: Dynamics of Macroscopic Swimmers at Moderate Reynolds Number Sustaining Chemical Wake Resonance
topic Fluid Dynamics
url https://arxiv.org/abs/2601.11264