Flying Snakes, Lizards, and Maple Seeds: The Dynamics of Gliders

Shane Ross

Professor in the Aerospace & Ocean Engineering, Virginia Tech

Seminar Information

Seminar Series
Dynamic Systems & Controls

Seminar Date - Time
October 7, 2022, 3:00 pm
-
4 pm

Seminar Location
EBUII 479, Von Karman-Penner Seminar Room


Abstract

Aerodynamic gliders, such as gliding animals or plant material, can exhibit a rich array of dynamical behavior. We discuss some recent efforts to reveal underlying physical mechanisms, using a hierarchy of mathematical models and experiments. Considering a simplified 2D model of passive descent, we find an attracting invariant manifold that acts as the dominant organizing feature of non-equilibrium dynamics in velocity space, providing a higher-dimensional analogue to the concept of terminal velocity—the terminal velocity manifold. From analysis of several gliding species, we find the pitch angle is a control parameter that can be exploited to modulate glide angle and glide speed. While this captures some features of gliding in the natural world, some animals have unusual features requiring special consideration. For instance, ‘flying snakes’ (genus Chrysopelea) are the only known limbless vertebrates capable of flight. When gliding, these animals use the unique behavior of aerial undulation, which does not provide propulsion, but instead enhances rotational stability, enabling gliding in these essentially 1-dimensional creatures. We use both experiments and simulation to elucidate this novel aerial control strategy. While the snake acts as one giant tail, other gliders, such as flying lizards (Draco dussumieri) may use their tail as a rudder while gliding. We also consider the related behavior of autorotating seeds, such as samaras from maple trees (genus Acer) which produce wind-dispersed seeds.

Speaker Bio

Shane Ross has been a Professor at Virginia Tech for 16 years. The Ross Dynamics Lab applies nonlinear dynamics, performing mathematical modeling, simulation, visualization, and experiments in several different fields, including: 3-body problem orbital mechanics, dispersal in the atmospheric and ocean, coupled translational-rotational dynamics, aerodynamic gliding (e.g., gliding animal dynamics, autorotating samaras), biomechanics, dynamic buckling of flexible structures, transport across the air-water interface, disease spread, and vehicle dynamics. Ross, a native Californian, has a BS and PhD from Caltech and is currently a visiting scholar at UCSD through November.