WATTS, Philip; FISH, Frank E.; Applied Fluids Engineering, Inc.; West Chester University: Fluid Dynamic and Maneuverability Aspects of Humpback Whale Flippers

Humpback whales capture prey through tight maneuvers, and their flippers appear to be an integral part of these maneuvers. Humpback whales possess tubercles on the leading edges of their high aspect ratio flippers. Our previous computer simulations of tubercles on airfoils have already shown that leading edge bumps can simultaneously increase lift 5% and decrease induced drag 10% at modest angles of attack. Recent experiments performed by others confirm that tubercles delay stall at large angles of attack and increase the maximum lift of an airfoil. These results support the argument that tubercles are functional adaptations. We simulate the fluid dynamic performance of an accurate representation of an actual humpback whale flipper with a panel method code. This allows us to quantify the influences of tubercles, planform, and aspect ratio on the forces generated by the flippers, in isolation and in concert. Depending on the chosen combination, we find flipper performance increases in the range of 10-50%. This may be sufficient evolutionary advantage to justify the costs of forming the flippers. We relate our findings of flipper performance to the maneuvers undertaken by humpback whales. We conclude that underwater maneuvers require a coordinated effort of the entire whale body.