Effects of Hydrodynamic Coupling Within a Self-Propelling Array of Pitching Hydrofoils

The dynamics of a body propelling itself through a fluid can be altered appreciably by the presence of additional self-propelling bodies nearby. Hydrodynamic coupling within an array of self-propelling bodies sharing a particular strategy for propulsion can cause the propulsive efficacy or energy efficiency of this strategy to deviate for the array overall from the efficacy or efficiency that would be observed by a body executing this strategy in isolation. This talk will address the self-propulsion of a planar array of hydrofoils pivoting periodically about their leading edges, mimicking a school of fishlike swimmers in a simplified way. Changes in the relative spacing of foils and phasing of oscillations within the array will be shown to influence the overall efficacy and efficiency of particular individual pivoting motions. Previous studies of similar systems have focused primarily on fixed arrays of hydrofoils in steady background flows rather than self-propelling arrays.