The Hong Kong University of Science and Technology
This study aimed at numerical simulation of the flow fields induced by a swallowtail butterfly based on the commercial software. Parameters such as the flapping frequency, the angle of attack, the wing shape, and the swallowtail effects on the aerodynamics were explored. The simulations show that the lift increases with the angle of attack first but decreases after angle of attack of 40˚ as a swallowtail butterfly-type wing is in gliding. However, the drag is shown to increase monotonically. Consequently, the lift-drag ratio has its maximum when the angle of attack is 10˚. The flapping flight has similar variations in the average lift, the drag and the lift-drag ratio of the gliding flight but the magnitudes increase with the increased flapping frequency. Through the 3D flow visualization, it was also found that the swallowtail can enhance the circulations around the trail during the downstroke when the flapping frequency is higher, regardless of the angle of attack. It is believed that the tail can enhance the flight stability of the Swallowtail butterfly.
The 4th Asian Symposium on Computational Heat Transfer and Fluid Flow 2013