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

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.