Effect of wing flexibility on phasing of tandem wings in forward flight

The dragonfly with two pairs of wings in tandem uses different phases between the wing pairs to suit the needs of the flight. Previous studies to understand the effect of phasing in forward flight are based on rigid wings. This is in contrast to the highly flexible dragonfly wings, with varying spanwise and chordwise flexibility. Here, we study flexible flapping wing simulations using Fluid Structure Interaction (FSI) in forward flight, at an advance ratio of 0.3 and Reynolds number of approximately 1300. The FSI simulations are carried out for phase 90$^{\circ}$ (hindwing leading), 0$^{\circ}$ (in-phase) and 180$^{\circ}$ (anti-phase). The performance of flexible wings will be compared with that of the rigid wings and the effect of flexibility will be discussed.