The effect of bio-inspired butterfly wing tip scales on the growth of a leading edge vortex

Previous studies with live Monarch butterflies have shown that removal of the scales can have a large effect on flight efficiency. One potential mechanism is if the scales found on the wing tips can affect tip-vortex growth. This study investigates the effect of butterfly wing tip scales on leading edge vortex (LEV) formation and growth. It is hypothesized that the addition of wing tip scales will decrease the vortex growth as the scales impede the motion of the flow around the tip of the wing. This would result in less energy loss to the tip vortices occurring during butterfly flight. A tow tank experiment was used to replicate the butterfly wing tip scales' effect through the movement of two plates in mineral oil. The first model is a smooth-edged flat plate while the other has 3D printed scales covering the leading edge which mimic the long, thin scales found on the wing tips of the Monarch butterfly. Digital Particle Image Velocimetry (DPIV) was then used to track the development of LEVs. Results will be presented.