Biography
Biography: Danesh Tafti
Abstract
Bats have highly dexterous and articulated membrane wings which can be manipulated by their hand digits during fl ight. Th is allows them to exert fi ne control over the shape and mechanical properties of the wing by fl exing their fi nger bones and changing the wing membrane stiff ness and shape. Many bat species are able to navigate and hunt in dense vegetation and can capture prey on the wing, oft en within very short time intervals and while operating in confi ned spaces. Challenges in studying bat fl ight include experimental data acquisition of wing kinematics and simulations of a highly deformable surface in space and time. An optical motion capture system of 21 cameras was used to mitigate wing self-occlusion while tracking 108 discrete marker points on the bat’s wings (Pratt's roundleaf bat, Hipposideros pratti) over the course of a meter-long fl ight. Th e surface of each wing is reconstructed in 3D space and time by the use of Proper Orthogonal Decomposition (POD) to fi lter noisy low energy modes of motion. Th e resulting kinematic model is interfaced with an unsteady incompressible fl ow
solver using the Immersed Boundary Method (IBM) and Large Eddy Simulation (LES) to characterize force production. To aid fundamental understanding, the complex wing kinematics is deconstructed into canonical descriptors of fl apping fl ight and related to aerodynamic force production.