Colloquium: Adrián Antón Álvarez (FPT)

Nature has been optimizing for millions of years the aerodynamics of dragonflies. The main goal of the present thesis is to understand these mechanisms so that they can be further applied in future bio-inspired designs. First, a single flapping wing is studied experimentally and numerically under different conditions. It is shown that dragonflies leading edge vortex is responsible for lift production. However, drag is also found to be a crucial contributor to the force balance that sustains dragonflies hovering. Additionally, wing corrugation effects improve hovering efficiency in the studied flow regime. Finally, wing-wing interaction effects are inspected numerically in a whole dragonfly. Phase changes between hindwings and forewings can maximize force production or be tuned to achieve a more stable and efficient hovering. However, not all phases are appropriate for maximum efficiency. Phase has to be tuned to maximize wake-capturing mechanisms in order to improve flying efficiency.

Supervisor: S. Hickel