CFD analyses of hummingbird escape maneuver

Hummingbirds are extremely agile among the flying animals. We reconstructed the full-body kinematics of the escape maneuver from high-speed videos of an initially hovering magnificent hummingbird when it was startled and then flew away. The kinematics was incorporated into 3D CFD simulation using a parallel immersed-boundary method. The aerodynamic forces and torques from the simulation were then used to perform analyses for the unsteady flight mechanics of the bird, where the inertial effects of the wings, trunk, and head were considered separately. Furthermore, both translational and rotational dynamics, i.e., the six DoF, were simulated in the process. The simulated body velocities generally agree with the experimental tracking of the bird. The cycle-to-cycle analyses suggest that the bird makes use of each half wing stroke in order to complete the rapid maneuver and that the maneuver cannot be achieved by a quasi-steady flight mechanics analysis in which that the forces and torques are averaged over the wingbeat cycles.