Computational Fluid Mechanics
Underactuated flapping wings
Flapping wing flight is one of the most energetically demanding modes of locomotion in nature. Wing pitching motion in insects has been hypothesized to be predominantly a passive phenomenon induced by inertial and aerodynamic effects with some active input at the wing hinge.
Tandem dragonfly wings with passive pitching in hovering flight are numerically simulated by using an immersed boundary-lattice Boltzmann method, to explore the passive pitching effects on the optimal aerodynamic performance. In the passive pitching model, the wing root is equivalent to a torsional spring.
Tandem rectangular plates flapping in phase are simulated with passive pitching for both forewing and hindwing.
Dragonfly wings flapping in phase with passive pitching: leading-edge vortices stretch spanwise and shift towards the wingtip
Dragonfly wings flapping out of phase with passive pitching.