Aerodynamic Characteristics of Owl-inspired Leading-Edge Serrations"

Owls are stealth raptors. It has been suggested that their stealth capabilities stem from their wings’ unique structure. One of these prominent elements is the so-called leading edge serrations: rigid miniature hook-like patterns placed at the primaries of leading edge. It has been hypothesized years ago that leading edge serrations alter the adjacent flow field partially to suppress aerodynamic noise, impact its aerodynamic performance and function as a passive flow control mechanism. Herein, we investigate the flow characteristics around an owl wing with serrated leading-edge geometry at intermediate chord-based Reynolds number (Re_c ~ 50,000). The flow around a Barn (Tyto alba) owl wing with and without serrations at different angles of attack are studied. The flow field is resolved by employing a DNS (Direct Numerical Simulation) approach, where unsteady incompressible Navier-Stokes equations are solved in a cartesian grid with sufficient resolution to resolve all the relevant flow scales. Disparities in the boundary layer structure as well as wake flow dynamics between the serrated and the unmodified wing are quantified to assess the influence of the serration geometry. Finally, the aerodynamic performance due to the presence of serrated leading edge is evaluated.