Snake-Inspired Aerial Gliding: Computational Analysis of the Fluid Dynamics and Aerodynamic Performances

Small animals’ locomotion, such as swimming, flapping, walking, and gliding motivated many bio-inspired robots. The flying snake happens to be a very unique species and a good representative of gliders. This research conducts a comprehensive numerical analysis on the aerodynamic phenomena of flying snakes, particularly focusing on their unique mode of locomotion known as aerial undulation. By simulating the flow dynamics around a bio-inspired snake-like model, this study extends the understanding of how Chrysopelea, the flying snake, utilizes a combination of horizontal and vertical undulations during gliding to manipulate airflow and enhance aerodynamic performance.

Employing an advanced incompressible flow solver with immersed boundary method and Tree-Local Mesh Refinement (TLMR), the research meticulously investigates the effects of angle of attack (AOA), undulation frequency, and Reynolds number on the formation of complex vortex structures, including leading-edge vortices (LEV), trailing-edge vortices (TEV), and tip vortices (TV).
The study reveals that horizontal undulations at an optimal 45° AOA significantly enhance lift, primarily through the modulation of LEVs. Furthermore, variations in undulation frequency and Reynolds number are shown to influence the stability of vortex structures and lift production, respectively. In exploring vertical bending locomotion, the paper highlights how changes in vertical wave undulation amplitudes and dorsal-ventral bending affect the aerodynamics, demonstrating that certain configurations can significantly augment lift and gliding efficiency. Additionally, the investigation into two-dimensional cross-sectional interactions of snake body segments uncovers the pivotal role of vortex-body interactions in modulating aerodynamic forces, offering insights into the potential for tailoring body posture for improved flight stability and efficiency.

By presenting the complex flow mechanisms and aerodynamic benefits of snake-like undulating and bending motions, this research provides a foundational basis for future explorations into more complex locomotion patterns of gliding animals. Moreover, the findings have implications for the design of bio-inspired robotic systems, potentially leading to the development of more efficient and maneuverable aerial vehicles. The synthesis of numerical simulations with detailed aerodynamic analyses opens new avenues for understanding the physics of natural gliders and translating these insights into innovative technological applications.