Classification of vortex patterns of oscillating foils in side-by-side configurations

The unsteady hydrodynamics of two pitching foils arranged in a side-by-side (parallel) configuration is examined for range Strouhal numbers, phase differences, oscillation amplitudes and separation distances. Three distinct vortex patterns are identified the wake maps, which include separated wake, merged transitional-merged wake. Furthermore, novel model introduced based on fundamental flow variables including velocity, location circulation dipole structures to quantitatively distinguish physical mechanism merging process also elucidated. When an oscillating foil experiences jet deflection phenomenon, secondary from primary street traverse other direction by making angle with its parent street. For in-phase parallel foils, lower interact upper under certain kinematic conditions. This interaction triggers influencing coherent part It unveiled that wakes leads enhancements propulsive efficiency increasing thrust generation without significant alteration power requirements. These attributed formation high-momentum street, possesses significantly larger due amalgamation vortices, major alterations evolution leading edge vortices. Thus, physics, thoroughly explored here, crucial providing insights future development control techniques efficient designs bio-inspired underwater propulsors.