68th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2015 — November 24, 2015)

V0059: Color coding vortices to understand flapping wing propulsion

Authors

• Thomas Mitchel, New York University, Courant Institute, Applied Math Lab
• Sophie Ramananarivo, New York University, Courant Institute, Applied Math Lab
• Leif Ristroph, New York University, Courant Institute, Applied Math Lab

DOI: https://doi.org/10.1103/APS.DFD.2015.GFM.V0059

While airplanes rely on the steady motion of a wing to generate aerodynamic forces, animals use more intricate motions to propel themselves through fluids, both during swimming and flying. The flapping motions cause the surrounding air or water to swirl around the edges of the wing or fin, and the manipulation of these vortices is important for the forces generated. Of course, the flows around bird wings and fish fins are usually invisible to us, so we mimicked these types of motions in the laboratory and devised a way to fluorescently color code the water flows created by a 3D-printed wing. The results from these experiments are shown in these videos, where one sees a beautiful dance between the red vortices generated at the front and the green ones generated at the back.