Hydrodynamics of self-propulsion near a boundary: predictions and accuracy of far-field approximations

TL;DR

This paper develops a multipole-based framework to predict how boundaries affect the swimming paths of microorganisms and synthetic swimmers, validating the approach against numerical simulations and explaining experimental observations.

Contribution

It introduces a general multipole description for studying boundary effects on self-propulsion and assesses the accuracy of far-field approximations across different swimmer models.

Findings

Far-field models accurately predict wall attraction and pitching dynamics.

Validation against numerical simulations confirms the model's applicability.

The framework helps explain experimental behaviors of swimmers near boundaries.

Abstract

The swimming trajectories of self-propelled organisms or synthetic devices in a viscous fluid can be altered by hydrodynamic interactions with nearby boundaries. We explore a multipole description of swimming bodies and provide a general framework for studying the fluid-mediated modifications to swimming trajectories. The validity of the far-field description is probed for a selection of model swimmers of varying geometry and propulsive activity by comparison with full numerical simulations. The reduced model is then used to deliver simple but accurate predictions of hydrodynamically generated wall attraction and pitching dynamics, and may help to explain a number of experimental results.